Distinct community structures of the fungal microbiome and respiratory health in adults with cystic fibrosis

BACKGROUND

The respiratory tract fungal microbiome in cystic fibrosis (CF) has been understudied despite increasing recognition of fungal pathogens in CF lung disease. We sought to better understand the fungal communities in adults with CF, and to define relationships between fungal profiles and clinical characteristics.

METHODS

We enrolled 66 adults with CF and collected expectorated sputum, spirometry, Cystic Fibrosis Questionnaire-revised, and clinical data. Fungi were molecularly profiled by sequencing of the internal transcribed spacer (ITS) region. Total fungal abundance was measured by quantitative PCR. Relative abundance and qPCR-corrected abundances were determined. Selective fungus culture identified cultivable fungi. Alpha diversity and beta diversity were measured and relationships with clinical parameters were interrogated.

RESULTS

Median age was 29 years and median FEV1 percent predicted 58%. Members of the Candida genus were the most frequent dominant taxa in CF sputum. Apiotrichum, Trichosporon, Saccharomyces cerevisiae, and Scedosporium were present in high relative abundance in few samples; whereas, Aspergillus species were detected at low levels. Higher FEV1% predicted and CFTR modulator use were associated with greater alpha-diversity. Chronic azithromycin use was associated with lower alpha-diversity. Patients with acute pulmonary had distinct fungal community composition compared to clinically stable subjects. Differing yeast species were mainly responsible for the community differences.

CONCLUSION

The respiratory tract fungal microbiome in adults with CF is associated with lung function, pulmonary exacerbation status, macrolide use, and CFTR modulator use. Future work to better understand fungal diversity in the CF airway and its impact on lung health is necessary.

Addition of cariogenic pathogens to complex oral microflora drives significant changes in biofilm compositions and functionalities

BACKGROUND

Dental caries is a microbe and sugar-mediated biofilm-dependent oral disease. Of particular significance, a virulent type of dental caries, known as severe early childhood caries (S-ECC), is characterized by the synergistic polymicrobial interaction between the cariogenic bacterium, Streptococcus mutans, and an opportunistic fungal pathogen, Candida albicans. Although cross-sectional studies reveal their important roles in caries development, these exhibit limitations in determining the significance of these microbial interactions in the pathogenesis of the disease. Thus, it remains unclear the mechanism(s) through which the cross-kingdom interaction modulates the composition of the plaque microbiome. Here, we employed a novel ex vivo saliva-derived microcosm biofilm model to assess how exogenous pathogens could impact the structural and functional characteristics of the indigenous native oral microbiota.

RESULTS

Through shotgun whole metagenome sequencing, we observed that saliva-derived biofilm has decreased richness and diversity but increased sugar-related metabolism relative to the planktonic phase. Addition of S. mutans and/or C. albicans to the native microbiome drove significant changes in its bacterial composition. In addition, the effect of the exogenous pathogens on microbiome diversity and taxonomic abundances varied depending on the sugar type. While the addition of S. mutans induced a broader effect on Kyoto Encyclopedia of Genes and Genomes (KEGG) ortholog abundances with glucose/fructose, S. mutans-C. albicans combination under sucrose conditions triggered unique and specific changes in microbiota composition/diversity as well as specific effects on KEGG pathways. Finally, we observed the presence of human epithelial cells within the biofilms via confocal microscopy imaging.

CONCLUSIONS

Our data revealed that the presence of S. mutans and C. albicans, alone or in combination, as well as the addition of different sugars, induced unique alterations in both the composition and functional attributes of the biofilms. In particular, the combination of S. mutans and C. albicans seemed to drive the development (and perhaps the severity) of a dysbiotic/cariogenic oral microbiome. Our work provides a unique and pragmatic biofilm model for investigating the functional microbiome in health and disease as well as developing strategies to modulate the microbiome. Video Abstract.

Administration of Bifidobacterium animalis subsp. lactis strain BB-12® in healthy children: characterization, functional composition, and metabolism of the gut microbiome

Introduction

The consumption of probiotics may influence children's gut microbiome and metabolome, which may reflect shifts in gut microbial diversity composition and metabolism. These potential changes might have a beneficial impact on health. However, there is a lack of evidence investigating the effect of probiotics on the gut microbiome and metabolome of children. We aimed to examine the potential impact of a two (Streptococcus thermophilus and Lactobacillus delbrueckii; S2) vs. three (S2 + Bifidobacterium animalis subsp. lactis strain BB-12) strain-supplemented yogurt.

Methods

Included in this study were 59 participants, aged one to five years old, recruited to phase I of a double-blinded, randomized controlled trial. Fecal samples were collected at baseline, after the intervention, and at twenty days post-intervention discontinuation, and untargeted metabolomics and shotgun metagenomics were performed.

Results

Shotgun metagenomics and metabolomic analyses showed no global changes in either intervention group's gut microbiome alpha or beta diversity indices, except for a lower microbial diversity in the S2 + BB12 group at Day 30. The relative abundance of the two and three intervention bacteria increased in the S2 and S2 + BB12 groups, respectively, from Day 0 to Day 10. In the S2 + BB12 group, the abundance of several fecal metabolites increased at Day 10, including alanine, glycine, lysine, phenylalanine, serine, and valine. These fecal metabolite changes did not occur in the S2 group.

Discussion

In conclusion, there were were no significant differences in the global metagenomic or metabolomic profiles between healthy children receiving two (S2) vs. three (S2 + BB12) probiotic strains for 10 days. Nevertheless, we observed a significant increase (Day 0 to Day 10) in the relative abundance of the two and three probiotics administered in the S2 and S2 + BB12 groups, respectively, indicating the intervention had a measurable impact on the bacteria of interest in the gut microbiome. Future research using longer probiotic intervention durations and in children at risk for gastrointestinal disorders may elucidate if functional metabolite changes confer a protective gastrointestinal effect.

Administration of Bifidobacterium animalis subsp. lactis Strain BB-12 ® in Healthy Children: Characterization, Functional Composition, and Metabolism of the Gut Microbiome

The consumption of probiotics may influence children's gut microbiome and metabolome, which may reflect shifts in gut microbial diversity composition and metabolism. These potential changes might have a beneficial impact on health. However, there is a lack of evidence investigating the effect of probiotics on the gut microbiome and metabolome of children. We aimed to examine the potential impact of a two ( Streptococcus thermophilus and Lactobacillus delbrueckii ; S2) vs . three (S2 + Bifidobacterium animalis subsp. lactis strain BB-12) strain-supplemented yogurt. Included in this study were 59 participants, aged one to five years old, recruited to phase I of a double-blinded, randomized controlled trial. Fecal samples were collected at baseline, after the intervention, and at twenty days post-intervention discontinuation, and untargeted metabolomics and shotgun metagenomics were performed. Shotgun metagenomics and metabolomic analyses showed no global changes in either intervention group's gut microbiome alpha or beta diversity indices. The relative abundance of the two and three intervention bacteria increased in the S2 and S2 + BB12 groups, respectively, from Day 0 to Day 10 . In the S2+BB12 group, the abundance of several fecal metabolites was reduced at Day 10 , including alanine, glycine, lysine, phenylalanine, serine, and valine. These fecal metabolite changes did not occur in the S2 group. Future research using longer probiotic intervention durations and in children at risk for gastrointestinal disorders may elucidate if functional metabolite changes confer a protective gastrointestinal effect.

Preterm infants at low risk for early-onset sepsis differ in early fecal microbiome assembly

Antibiotics are administered near-universally to very low birth weight (VLBW) infants after birth for suspected early-onset sepsis (EOS). We previously identified a phenotypic group of VLBW infants, referred to as low-risk for EOS (LRE), whose risk of EOS is low enough to avoid routine antibiotic initiation. In this cohort study, we compared 18 such infants with 30 infants categorized as non-LRE to determine if the lower risk of pathogen transmission at birth is accompanied by differences in microbiome acquisition and development. We did shotgun metagenomic sequencing of 361 fecal samples obtained serially. LRE infants had a higher human-to-bacterial DNA ratio than non-LRE infants in fecal samples on days 1-3 after birth, confirming lower bacterial acquisition among LRE infants. The microbial diversity and composition in samples from days 4-7 differed between the groups with a predominance of Staphylococcus epidermidis in LRE infants and Enterobacteriaceae sp. in non-LRE infants. Compositional differences were congruent with the distribution of virulence factors and antibiotic resistant genes. After the first week, the overall composition was similar, but changes in relative abundance for several taxa with increasing age differed between groups. Of the nine late-onset bacteremia episodes, eight occurred in non-LRE infants. Species isolated from the blood culture was detected in the pre-antibiotic fecal samples of the infant for all episodes, though these species were also found in infants without bacteremia. In conclusion, LRE infants present a distinct pattern of microbiome development that is aligned with their low risk for EOS. Further investigation to determine the impact of these differences on later outcomes such as late-onset bacteremia is warranted.

Innate type 2 immunity controls hair follicle commensalism by Demodex mites

Demodex mites are commensal parasites of hair follicles (HFs). Normally asymptomatic, inflammatory outgrowth of mites can accompany malnutrition, immune dysfunction, and aging, but mechanisms restricting Demodex outgrowth are not defined. Here, we show that control of mite HF colonization in mice required group 2 innate lymphoid cells (ILC2s), interleukin-13 (IL-13), and its receptor, IL-4Ra-IL-13Ra1. HF-associated ILC2s elaborated IL-13 that attenuated HFs and epithelial proliferation at anagen onset; in their absence, Demodex colonization led to increased epithelial proliferation and replacement of gene programs for repair by aberrant inflammation, leading to the loss of barrier function and HF exhaustion. Humans with rhinophymatous acne rosacea, an inflammatory condition associated with Demodex, had increased HF inflammation with decreased type 2 cytokines, consistent with the inverse relationship seen in mice. Our studies uncover a key role for skin ILC2s and IL-13, which comprise an immune checkpoint that sustains cutaneous integrity and restricts pathologic infestation by colonizing HF mites.

Innate type 2 immunity controls hair follicle commensalism by Demodex mites

Demodex mites are obligate commensal parasites of hair follicles (HF) in mammals. Normally asymptomatic, inflammatory outgrowth of mites can accompany malnutrition, immune dysfunction and aging, but mechanisms restricting Demodex outgrowth and pathogenesis are not defined. Here, we show that control over mite HF colonization of mice requires ILC2s, IL-13, and its receptor IL-4Ra, but not IL-4 or the adaptive immune system. Epithelial HF-associated ILC2s elaborate IL-13 that attenuates HF and epithelial cell proliferation at anagen onset; in their absence, Demodex colonization leads to increased epithelial proliferation and replacement of gene programs for repair by aberrant inflammatory programs leading to loss of barrier function and premature HF exhaustion over time. Humans with rhinophymatous acne rosacea, a nasal inflammatory condition associated with a high burden of Demodex, had increased HF inflammatory cells with decreased type 2 cytokines, consistent with the inverse relationship seen in mice. Our studies uncover a critical role for skin ILC2s and IL-13, which comprise an immune checkpoint necessary to sustain cutaneous integrity and restrict pathologic infestation by colonizing HF mites.

This work was supported by the National Institutes of Health (AR007175 to R.R.R.G. and M.S.F, AR075880 to R.R.R.G, HL140868 to M.E.K., DK121476 to C.E.O., AI159229 to W.D., AR074556 to M.S.F., AI026918 and HL107202 to R.M.L.), Dermatology Foundation (R.R.R.G., M.S.F.), A.P. Giannini Foundation (R.R.R.G, M.E.K.), Robert Wood Johnson Foundation (R.R.R.G.), Howard Hughes Medical Institute (R.M.L.), University of California Tobacco-Related Disease Research Program (T29IP0554 to J.S.F.), and the Sandler Asthma Basic Research Center at the University of California San Francisco. R.E. Díaz was supported by NSF GRFP (#1650113). R.E. Díaz is a Howard Hughes Medical Institute Gilliam Fellow (#GT11377).

The Mucosally-Adherent Rectal Microbiota Contains Features Unique to Alcohol-Related Cirrhosis

Most studies examining correlations between the gut microbiota and disease states focus on fecal samples due to ease of collection, yet there are distinct differences when compared to samples collected from the colonic mucosa. Although fecal microbiota has been reported to be altered in cirrhosis, correlation with mucosal microbiota characterized via rectal swab has not been previously described in this patient population. We conducted a cross-sectional analysis using 39 stool and 39 rectal swabs from adult patients with cirrhosis of different etiologies and performed shotgun metagenomic sequencing. Bacterial growth studies were performed with Escherichia coli. Two asaccharolytic bacterial taxa, Finegoldia magna and Porphyromonas asaccharolytica, were increased in rectal swabs relative to stool (FDR < 0.01). Genomic analysis of the microbiome revealed 58 genes and 16 pathways that differed between stool and rectal swabs (FDR < 0.05), where rectal swabs were enriched for pathways associated with protein synthesis and cellular proliferation but decreased in carbohydrate metabolism. Although no features in the fecal microbiome differentiated cirrhosis etiologies, the mucosal microbiome revealed decreased abundances of E. coli and Enterobacteriaceae in alcohol-related cirrhosis relative to non-alcohol related cirrhosis (FDR < 0.05). In vitro bacterial culture studies showed that physiological concentrations of ethanol and its oxidative metabolites inhibited E. coli growth in a pH- and concentration-dependent manner. Characterization of the mucosally associated gut microbiome via rectal swab revealed findings consistent with amino acid/nitrogen abundance versus carbohydrate limitation in the mucosal microenvironment as well as unique features of alcohol-related cirrhosis possibly consistent with the influence of host-derived metabolites on the composition of mucosally adherent microbiota.

A Randomized Trial Comparing the Specific Carbohydrate Diet to a Mediterranean Diet in Adults With Crohn's Disease

BACKGROUND & AIMS

This study compared the effectiveness of the Specific Carbohydrate Diet (SCD) to the Mediterranean diet (MD) as treatment for Crohn's disease (CD) with mild to moderate symptoms.

METHODS

Adult patients with CD and with mild-to-moderate symptoms were randomly assigned 1:1 to consume the MD or SCD for 12 weeks. For the first 6 weeks, participants received prepared meals and snacks according to their assigned diet. After 6 weeks, participants were instructed to follow the diet independently. The primary outcome was symptomatic remission at week 6. Key secondary outcomes at week 6 included fecal calprotectin (FC) response (FC <250 μg/g and reduction by >50% among those with baseline FC >250 μg/g) and C-reactive protein (CRP) response (high-sensitivity CRP <5 mg/L and >50% reduction from baseline among those with high-sensitivity CRP >5 mg/L).

RESULTS

The study randomized 194 patients, and 191 were included in the efficacy analyses. The percentage of participants who achieved symptomatic remission at week 6 was not superior with the SCD (SCD, 46.5%; MD, 43.5%; P = .77). FC response was achieved in 8 of 23 participants (34.8%) with the SCD and in 4 of 13 participants (30.8%) with the MD (P = .83). CRP response was achieved in 2 of 37 participants (5.4%) with the SCD and in 1 of 28 participants (3.6%) with the MD (P = .68).

CONCLUSIONS

The SCD was not superior to the MD to achieve symptomatic remission, FC response, and CRP response. CRP response was uncommon. Given these results, the greater ease of following the MD and other health benefits associated with the MD, the MD may be preferred to the SCD for most patients with CD with mild to moderate symptoms. ClinicalTrials.gov Identifier: NCT03058679.

miR-9a mediates the role of Lethal giant larvae as an epithelial growth inhibitor in Drosophila

Drosophila lethal giant larvae (lgl) encodes a conserved tumor suppressor with established roles in cell polarity, asymmetric division, and proliferation control. Lgl's human orthologs, HUGL1 and HUGL2, are altered in human cancers, however, its mechanistic role as a tumor suppressor remains poorly understood. Based on a previously established connection between Lgl and Fragile X protein (FMRP), a miRNA-associated translational regulator, we hypothesized that Lgl may exert its role as a tumor suppressor by interacting with the miRNA pathway. Consistent with this model, we found that lgl is a dominant modifier of Argonaute1 overexpression in the eye neuroepithelium. Using microarray profiling we identified a core set of ten miRNAs that are altered throughout tumorigenesis in Drosophila lgl mutants. Among these are several miRNAs previously linked to human cancers including miR-9a, which we found to be downregulated in lgl neuroepithelial tissues. To determine whether miR-9a can act as an effector of Lgl in vivo, we overexpressed it in the context of lgl knock-down by RNAi and found it able to reduce the overgrowth phenotype caused by Lgl loss in epithelia. Furthermore, cross-comparisons between miRNA and mRNA profiling in lgl mutant tissues and human breast cancer cells identified thrombospondin (tsp) as a common factor altered in both fly and human breast cancer tumorigenesis models. Our work provides the first evidence of a functional connection between Lgl and the miRNA pathway, demonstrates that miR-9a mediates Lgl's role in restricting epithelial proliferation, and provides novel insights into pathways controlled by Lgl during tumor progression.

Summary: Mir-9a overexpression can suppress the overgrowth phenotype caused by Lgl knock-down in epithelia. Gene profiling identifies pathways dysregulated in lgl mutants and shared features between flies and human cancer cells.

SCFSlimb ubiquitin ligase suppresses condensin II-mediated nuclear reorganization by degrading Cap-H2

Condensin complexes play vital roles in chromosome condensation during mitosis and meiosis. Condensin II uniquely localizes to chromatin throughout the cell cycle and, in addition to its mitotic duties, modulates chromosome organization and gene expression during interphase. Mitotic condensin activity is regulated by phosphorylation, but mechanisms that regulate condensin II during interphase are unclear. Here, we report that condensin II is inactivated when its subunit Cap-H2 is targeted for degradation by the SCF(Slimb) ubiquitin ligase complex and that disruption of this process dramatically changed interphase chromatin organization. Inhibition of SCF(Slimb) function reorganized interphase chromosomes into dense, compact domains and disrupted homologue pairing in both cultured Drosophila cells and in vivo, but these effects were rescued by condensin II inactivation. Furthermore, Cap-H2 stabilization distorted nuclear envelopes and dispersed Cid/CENP-A on interphase chromosomes. Therefore, SCF(Slimb)-mediated down-regulation of condensin II is required to maintain proper organization and morphology of the interphase nucleus.

Motor neurons and glia exhibit specific individualized responses to TDP-43 expression in a Drosophila model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal disease characterized by complex neuronal and glial phenotypes. Recently, RNA-based mechanisms have been linked to ALS via RNA-binding proteins such as TDP-43, which has been studied in vivo using models ranging from yeast to rodents. We have developed a Drosophila model of ALS based on TDP-43 that recapitulates several aspects of pathology, including motor neuron loss, locomotor dysfunction and reduced survival. Here we report the phenotypic consequences of expressing wild-type and four different ALS-linked TDP-43 mutations in neurons and glia. We show that TDP-43-driven neurodegeneration phenotypes are dose- and age-dependent. In motor neurons, TDP-43 appears restricted to nuclei, which are significantly misshapen due to mutant but not wild-type protein expression. In glia and in the developing neuroepithelium, TDP-43 associates with cytoplasmic puncta. TDP-43-containing RNA granules are motile in cultured motor neurons, although wild-type and mutant variants exhibit different kinetic properties. At the neuromuscular junction, the expression of TDP-43 in motor neurons versus glia leads to seemingly opposite synaptic phenotypes that, surprisingly, translate into comparable locomotor defects. Finally, we explore sleep as a behavioral readout of TDP-43 expression and find evidence of sleep fragmentation consistent with hyperexcitability, a suggested mechanism in ALS. These findings support the notion that although motor neurons and glia are both involved in ALS pathology, at the cellular level they can exhibit different responses to TDP-43. In addition, our data suggest that individual TDP-43 alleles utilize distinct molecular mechanisms, which will be important for developing therapeutic strategies.

Interaction of DNA-binding proteins with the 5'-flanking region of a cytokinin-responsive cucumber hydroxypyruvate reductase gene

Transcription of the cucumber hpr-A gene is responsive to cytokinin and light. To investigate the molecular basis for transcriptional regulation by cytokinin, we have identified DNA sequences and proteins that may be involved in the regulation of hpr-A gene expression. Transient expression assays in etiolated cucumber cotyledons indicate that the 315 bp fragment (-382 to -67) contains sequences necessary for cytokinin responsiveness of the luciferase reporter gene. Band shift assays detected cytokinin-enhanced and -reduced protein binding sites in a 97 bp fragment (-382 to -285) upstream of the hpr-A gene. DNase I footprinting identified two protein-protected sites, a 15 bp sequence, 5'-AAATGACGAAAATGC-3', that contains an as-1 TGACG motif found in other plant promoters, and a 13 bp sequence, 5'-AAGATTGATTGAG-3', of unknown function. Two-dimensional band shift analysis of the cytokinin-responsive DNA protein complex revealed the presence of six DNA protein interactions. Band shift assays showed that cytokinin and light have different effects on the interaction of nuclear proteins to the 97 bp fragment of the hpr-A gene. These data suggest that cytokinin and light do not share identical signal transduction pathways in regulating hpr-A gene expression.

FastTag Nucleic Acid Labeling System: a versatile method for incorporating haptens, fluorochromes and affinity ligands into DNA, RNA and oligonucleotides

The FastTag Nucleic Acid Labeling System couples haptens, fluorochromes or affinity ligands to any nucleic acid by attaching a universal, photo-or heat-activatable moiety to which any sulfhydryl-reactive compound can be linked. To demonstrate the versatility of the FastTag system, we have labeled DNA, RNA and oligonucleotide probes with a variety of maleimide-coupled moieties and have used these probes in several applications. In Southern hybridization analyses, RNA probes labeled using FastTag FL (fluorescein) detected 0.04 pg of target DNA. Human satellite DNA clones labeled using FastTag FL or FastTag Biotin detected the corresponding sequences in human chromosome spreads and interphase nuclei by fluorescence in situ hybridization. An antisense oligonucleotide probe cocktail complementary to human proinsulin transcripts labeled using FastTag DNP (dinitrophenyl) detected, in situ, the appropriate transcripts in pancreatic tissue sections. Oligonucleotide primers labeled with FastTag FL were used to PCR-amplify a genomic DNA fragment, which was then detected immunologically. Finally, we discuss how DNA labeled with FastTag Fucose can be bound to a fucose-binding affinity matrix and eluted under mild conditions.

Transgenic analysis of the 5'- and 3'-flanking regions of the NADH-dependent hydroxypyruvate reductase gene from Cucumis sativus L

The 5'- and 3'-flanking regions of HPRA, a cucumber gene that encodes hydroxypyruvate reductase, were evaluated for regulatory activity with respect to light responsiveness and organ specificity. To define the functional regions of the 5'-flanking region of HPRA, a series of deletions was generated and the remaining portions fused to the beta-glucuronidase (GUS) reporter gene (uidA) containing a minimal 35S promoter truncated at -90. The region from -66 to +39 was found to be necessary for light-regulated expression of the uidA reporter gene, while the region from -382 to -67 was found to be necessary for its leaf-specific expression. Further deletion of the HPRA 5' flanking region to -590 resulted in high levels of root expression, suggesting the presence of a negative regulatory element responsible for silencing root expression of the HPRA gene between -590 and -383. The 3'-flanking region of the HPRA gene downstream of the polyadenylation site contains several sequence motifs resembling regulatory elements present in the promoters of several light-responsive genes. An 823 bp portion of the HPRA 3'-flanking region containing these putative regulatory elements enhanced GUS expression in leaves when placed downstream of the uidA reporter gene in the forward orientation, but not in the reverse orientation. When placed 5' of the -90 35S promoter, the 823 bp fragment enhanced slightly, independently of orientation, the root tip-specific expression pattern intrinsic to the -90 35S promoter, indicating that in some cases this region can act as a transcriptional enhancer.

Photooxidative Destruction of Chloroplasts Leads to Reduced Expression of Peroxisomal NADH-Dependent Hydroxypyruvate Reductase in Developing Cucumber Cotyledons

Photooxidative destruction of chloroplasts by exposure of norflurazon-treated cucumber (Cucumis sativus L.) seedlings to white light leads to reduced levels of the nuclear-encoded, peroxisomal enzyme hydroxypyruvate reductase. The partial reduction in hydroxypyruvate reductase activity under photooxidative conditions is accompanied by reductions in levels of hydroxypyruvate reductase protein and transcript. The low level of hydroxypyruvate reductase gene expression in the dark is not affected by norflurazon, and nonphotooxidizing far-red light is able to induce significant increases in hydroxypyruvate reductase expression even in the presence of norflurazon. We conclude that intact plastids are required for maximal expression of hydroxypyruvate reductase in the light and that the plastids affect hydroxypyruvate reductase gene expression at a pretranslational level.

Auxin physiology of the tomato mutant diageotropica

The tomato (Lycopersicon esculentum, Mill.) mutant diageotropica (dgt) exhibits biochemical, physiological, and morphological abnormalities that suggest the mutation may have affected a primary site of auxin perception or action. We have compared two aspects of the auxin physiology of dgt and wild-type (VFN8) seedlings: auxin transport and cellular growth parameters. The rates of basipetal indole-3-acetic acid (IAA) polar transport are identical in hypocotyl sections of the two genotypes, but dgt sections have a slightly greater capacity for IAA transport. 2,3,5-Triiodobenzoic acid and ethylene reduce transport in both mutant and wild-type sections. The kinetics of auxin uptake into VFN8 and dgt sections are nearly identical. These results make it unlikely that an altered IAA efflux carrier or IAA uptake symport are responsible for the pleiotropic effects resulting from the dgt mutation. The lack of auxin-induced cell elongation in dgt plants is not due to insufficient turgor, as the osmotic potential of dgt cell sap is less (more negative) than that of VFN8. An auxin-induced increase in wall extensibility, as measured by the Instron technique, only occurs in the VFN8 plants. These data suggest dgt hypocotyls suffer a defect in the sequence of events culminating in auxin-induced cell wall loosening.

Development and utility of a monoclonal-antibody-based, highly sensitive immunoradiometric assay of thyrotropin

Using improved selection techniques, we isolated four monoclonal antibodies with high affinity for human thyrotropin (Ka = 1.6 X 10(8) to 2.6 X 10(10) L/mol). We used two of these in an immunoradiometric assay (IRMA) that also incorporates a novel phase-separation technology (Sucrosep TSH IRMA, Boots-Celltech). This assay's very low detection limit for TSH (0.03-0.08 milli-int. unit/L) and wide working range (0-250 milli-int. unit/L) allow the differential diagnosis of hypothyroid, euthyroid, and hyperthyroid patients. We compare the utility of this IRMA with that of a RIA for patients with various thyroid disorders. As determined by IRMA, a normal concentration of TSH in serum excludes hyperthyroidism or hypothyroidism, whereas an undetectable serum TSH concentration (less than 0.08 milli-int. unit/L) accurately predicts an abnormality in thyroid gland function.

Development and utility of a monoclonal-antibody-based, highly sensitive immunoradiometric assay of thyrotropin

Using improved selection techniques, we isolated four monoclonal antibodies with high affinity for human thyrotropin (Ka = 1.6 X 10(8) to 2.6 X 10(10) L/mol). We used two of these in an immunoradiometric assay (IRMA) that also incorporates a novel phase-separation technology (Sucrosep TSH IRMA, Boots-Celltech). This assay's very low detection limit for TSH (0.03-0.08 milli-int. unit/L) and wide working range (0-250 milli-int. unit/L) allow the differential diagnosis of hypothyroid, euthyroid, and hyperthyroid patients. We compare the utility of this IRMA with that of a RIA for patients with various thyroid disorders. As determined by IRMA, a normal concentration of TSH in serum excludes hyperthyroidism or hypothyroidism, whereas an undetectable serum TSH concentration (less than 0.08 milli-int. unit/L) accurately predicts an abnormality in thyroid gland function.

Regulation of immunoreactive beta-endorphin release from rat pituitary cell culture

The release of immunoreactive beta-endorphin from rat anterior pituitary cells in culture was studied by radioimmunoassay and gel-filtration chromatography. Two forms of immunoreactivity were detected corresponding to beta-lipotrophin (beta-LPH) and beta-endorphin. Cells were found to release beta-endorphin-like immunoreactivity (beta-endorphin LIR) into the culture medium for up to 10 days with a trough in release occurring between days 2-4. The ratio of beta-LPH to beta-endorphin released remained constant during the course of culture. After 4 days in culture beta-endorphin LIR release was constant and responsive to modulation. Incubation with lysine-vasopressin (0.1 units/ml) produced a two- to threefold increase in release and dexamethasone (10 (-6) mol/l) suppressed release to 33% of controls. Neither stimulation nor suppression resulted in a change in the ratio of beta-LPH to beta-endorphin released. Dexamethasone suppression was not overcome by removal of dexamethasone or addition of vasopressin.