Discovery of small molecule agonists of the Relaxin Family Peptide Receptor 2

The relaxin/insulin-like family peptide receptor 2 (RXFP2) belongs to the family of class A G-protein coupled receptors (GPCRs) and it is the only known target for the insulin-like factor 3 peptide (INSL3). The importance of this ligand-receptor pair in the development of the gubernacular ligament during the transabdominal phase of testicular descent is well established. More recently, RXFP2 has been implicated in maintaining healthy bone formation. In this report, we describe the discovery of a small molecule series of RXFP2 agonists. These compounds are highly potent, efficacious, and selective RXFP2 allosteric agonists that induce gubernacular invagination in mouse embryos, increase mineralization activity in human osteoblasts in vitro, and improve bone trabecular parameters in adult mice. The described RXFP2 agonists are orally bioavailable and display favorable pharmacokinetic properties, which allow for future evaluation of the therapeutic benefits of modulating RXFP2 activation in disease models.

Specific small molecule RXFP2 agonists with favorable pharmacokinetic properties induce gubernacular invagination in mouse embryos, increase mineralization activity in human osteoblasts in vitro, and improve bone trabecular parameters in adult mice.

Human Defensin-5 (HD-5) and HD-6 mRNA Produced by Intestinal Crypt Paneth Cells are Decreased in Fecal Samples of Patients Positive for SARS-CoV2

Alpha-defensins (AD) are antimicrobial peptides (AMP) that are found on mucosal surfaces, providing innate immune defense against pathogens. Human defensin-5 (HD-5) and HD-6 are AD produced only by Paneth cells of small intestinal crypts. SARS-CoV2 virus has been shown to infect the small intestinal cells via the ACE2 receptor and suppress inflammation in the gut. HD-5 and HD-6 bind ACE2 to prevent entry to intestinal cells. Based on the observation that human beta defensin-1 (hBD-1) is downregulated by influenza virus in airway epithelial cells, we hypothesized that HD-5 and HD-6 could be similarly downregulated by SARS-CoV2. To examine this in situ, we sampled patient cohorts with similar co-morbidities, with and without SARS-CoV2 positivity, for HD-5 and HD-6 gene expression via qRT-PCR. Stool samples were collected from all patients, diluted in Qiagen RNA Later and frozen at −80°C prior to total RNA extraction. Results revealed a significant decrease in both HD-5 (p=0.000006) and HD-6 (p=0.002) of SARS-CoV2 positive patients compared with non-Covid19 patients negative for SARS-CoV2. The results were consistent in fecal swabs or fecal streams. Gene expression in other significant markers of inflammation were also blunted: sPLA-2 (p=0.006), alpha-1-anti-trypsin (p=0.0001) and trypsin 2 (p=0.005). Other gut inflammatory markers PSTI, HIP/PAP, trypsin 3 and IL-8 were unchanged. There was a trend in IL-8 upregulation in Covid19 patients. This is the first demonstration of defensin mRNA detection in stool samples. The results suggest that decreasing AMPs may be a mechanism by which the virus increases its chance for survival.

Supported by R21DE028378

Defining baseline variability of serum tryptase levels improves accuracy in identifying anaphylaxis

BACKGROUND

Acute increases of ≥20% + 2 ng/mL (20 + 2 rule) over basal serum tryptase (BST) is the recommended threshold supporting a clinical diagnosis of anaphylaxis. Prospective studies have demonstrated high sensitivity for this algorithm after parenteral exposure, but specificity has not been evaluated.

OBJECTIVE

We sought to define a serum tryptase change that distinguishes baseline variability from anaphylaxis on the basis of intraindividual variation in BST.

METHODS

Ninety-three total subjects with atopy (n = 62) or hereditary α-tryptasemia (HαT) (n = 31) and ≥2 BST measurements were identified. Sequential BST variability measurements were modeled and threshold ratios that optimized sensitivity and/or specificity determined. Models were tested in 22 individuals with physician-diagnosed anaphylaxis and validated in independent cohorts of individuals with HαT (n = 33), indolent systemic mastocytosis (ISM) (n = 52), and ISM + HαT (n = 12). Mature tryptase levels were measured in HαT (n = 19) and ISM (n = 20). An online application was developed for clinical use.

RESULTS

As a result of BST variability, 9.7% (9/93) of primary cohort patients, and 18% (6/33) of HαT, 30% (16/53) of ISM, and 25% (3/12) of ISM + HαT patients from validation cohorts met the 20 + 2 rule despite absent immediate hypersensitivity symptoms; mature tryptase was noncontributory among individuals with HαT or ISM at baseline. A ratio of acute tryptase/BST exceeding 1.685 provided the optimized diagnostic rule for jointly maximizing sensitivity and specificity. Statistically significant improvement in specificity relative to the 20 + 2 rule was observed among individuals with elevated BST caused by HαT and ISM.

CONCLUSIONS

Using an acute tryptase/BST ratio of 1.685 improves specificity of measured changes among individuals with HαT and ISM while maintaining high sensitivity for confirmation of anaphylaxis.

OUP accepted manuscript

Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by reduced expression of the survival motor neuron (SMN) protein. Current disease-modifying therapies increase SMN levels and dramatically improve survival and motor function of SMA patients. Nevertheless, current treatments are not cures and autopsy data suggest that SMN induction is variable. Our group and others have shown that combinatorial approaches that target different modalities can improve outcomes in rodent models of SMA. Here we explore if slowing SMN protein degradation and correcting SMN splicing defects could synergistically increase SMN production and improve the SMA phenotype in model mice. We show that co-administering ML372, which inhibits SMN ubiquitination, with an SMN-modifying antisense oligonucleotide (ASO) increases SMN production in SMA cells and model mice. In addition, we observed improved spinal cord, neuromuscular junction and muscle pathology when ML372 and the ASO were administered in combination. Importantly, the combinatorial approach resulted in increased motor function and extended survival of SMA mice. Our results demonstrate that a combination of treatment modalities synergistically increases SMN levels and improves pathophysiology of SMA model mice over individual treatment.

Anti-apoptotic and Matrix Remodeling Actions of a Small Molecule Agonist of the Human Relaxin Receptor, ML290 in Mice With Unilateral Ureteral Obstruction

Diseases, such as diabetes and hypertension, often lead to chronic kidney failure. The peptide hormone relaxin has been shown to have therapeutic effects in various organs. In the present study, we tested the hypothesis that ML290, a small molecule agonist of the human relaxin receptor (RXFP1), is able to target the kidney to remodel the extracellular matrix and reduce apoptosis induced by unilateral ureteral obstruction (UUO). UUO was performed on the left kidney of humanized RXFP1 mice, where the right kidneys served as contralateral controls. Mice were randomly allocated to receive either vehicle or ML290 (30 mg/kg) via daily intraperitoneal injection, and kidneys were collected for apoptosis, RNA, and protein analyses. UUO significantly increased expression of pro-apoptotic markers in both vehicle- and ML290-treated mice when compared to their contralateral control kidneys. Specifically, Bax expression and Erk1/2 activity were upregulated, accompanied by an increase of TUNEL-positive cells in the UUO kidneys. Additionally, UUO induced marked increase in myofibroblast differentiation and aberrant remodeling on the extracellular matrix. ML290 suppressed these processes by promoting a reduction of pro-apoptotic, fibroblastic, and inflammatory markers in the UUO kidneys. Finally, the potent effects of ML290 to remodel the extracellular matrix were demonstrated by its ability to reduce collagen gene expression in the UUO kidneys. Our data indicate that daily administration of ML290 has renal protective effects in the UUO mouse model, specifically through its anti-apoptotic and extracellular matrix remodeling properties.

The gut microbiome of COVID-19 recovered patients returns to uninfected status in a minority-dominated United States cohort

To investigate the relationship between intestinal microbiota and SARS-CoV-2-mediated pathogenicity in a United States, majority African American cohort. We prospectively collected fecal samples from 50 SARS-CoV-2 infected patients, 9 SARS-CoV-2 recovered patients, and 34 uninfected subjects seen by the hospital with unrelated respiratory medical conditions (controls). 16S rRNA sequencing and qPCR analysis was performed on fecal DNA/RNA. The fecal microbial composition was found to be significantly different between SARS-CoV-2 patients and controls (PERMANOVA FDR-P = .004), independent of antibiotic exposure. Peptoniphilus, Corynebacterium and Campylobacter were identified as the three most significantly enriched genera in COVID-19 patients compared to controls. Actively infected patients were also found to have a different gut microbiota than recovered patients (PERMANOVA FDR-P = .003), and the most enriched genus in infected patients was Campylobacter, with Agathobacter and Faecalibacterium being enriched in the recovered patients. No difference in microbial community structure between recovered patients and uninfected controls was observed, nor a difference in alpha diversity between the three groups. 24 of the 50 COVID-19 patients (48%) tested positive via RT-qPCR for fecal SARS-CoV-2 RNA. A significant difference in gut microbial composition between SARS-CoV-2 positive and negative samples was observed, with Klebsiella and Agathobacter being enriched in the positive cohort. No significant associations between microbiome composition and disease severity was found. The intestinal microbiota is sensitive to the presence of SARS-CoV-2, with increased relative abundance of genera (Campylobacter, Klebsiella) associated with gastrointestinal (GI) disease. Further studies are needed to investigate the functional impact of SARS-CoV-2 on GI health.

Therapeutic effects of a small molecule agonist of the relaxin receptor ML290 in liver fibrosis

Fibrosis is an underlying cause of cirrhosis and hepatic failure resulting in end stage liver disease with limited pharmacological options. The beneficial effects of relaxin peptide treatment were demonstrated in clinically relevant animal models of liver fibrosis. However, the use of relaxin is problematic because of a short half-life. The aim of this study was to test the therapeutic effects of recently identified small molecule agonists of the human relaxin receptor, relaxin family peptide receptor 1 (RXFP1). The lead compound of this series, ML290, was selected based on its effects on the expression of fibrosis-related genes in primary human stellate cells. RNA sequencing analysis of TGF-β1-activated LX-2 cells showed that ML290 treatment primarily affected extracellular matrix remodeling and cytokine signaling, with expression profiles indicating an antifibrotic effect of ML290. ML290 treatment in human liver organoids with LPS-induced fibrotic phenotype resulted in a significant reduction of type I collagen. The pharmacokinetics of ML290 in mice demonstrated its high stability in vivo, as evidenced by the sustained concentrations of compound in the liver. In mice expressing human RXFP1 gene treated with carbon tetrachloride, ML290 significantly reduced collagen content, α-smooth muscle actin expression, and cell proliferation around portal ducts. In conclusion, ML290 demonstrated antifibrotic effects in liver fibrosis.-Kaftanovskaya, E. M., Ng, H. H., Soula, M., Rivas, B., Myhr, C., Ho, B. A., Cervantes, B. A., Shupe, T. D., Devarasetty, M., Hu, X., Xu, X., Patnaik, S., Wilson, K. J., Barnaeva, E., Ferrer, M., Southall, N. T., Marugan, J. J., Bishop, C. E., Agoulnik, I. U., Agoulnik, A. I. Therapeutic effects of a small molecule agonist of the relaxin receptor ML290 in liver fibrosis.

Optimization of the first small-molecule relaxin/insulin-like family peptide receptor (RXFP1) agonists: Activation results in an antifibrotic gene expression profile

A dose responsive quantitative high throughput screen (qHTS) of >350,000 compounds against a human relaxin/insulin-like family peptide receptor (RXFP1) transfected HEK293 cell line identified 2-acetamido-N-phenylbenzamides 1 and 3 with modest agonist activity. An extensive structure-activity study has been undertaken to optimize the potency, efficacy, and physical properties of the series, resulting in the identification of compound 65 (ML-290), which has excellent in vivo PK properties with high levels of systemic exposure. This series, exemplified by 65, has produced first-in-class small-molecule agonists of RXFP1 and is a potent activator of anti-fibrotic genes.

Isolation of sterol mutants inChlamydomonas reinhardi: Chromatographic analyses

Several sterol mutants ofChlamydomonas reinhardi were isolated by selecting for single colonies resistant to the polyene antibiotic, nystatin. The sterol profiles of three isolates-KD7, KD16, and KD21-as well as a wild type strain (137C) were determined by gas liquid chromatography and mass spectrometry. The wild type strain contained ergosterol (C28-5,7,22-triene) as the predominant sterol, with smaller amounts of a C28-5,7-diene, a C28-7-ene, and C-24 ethyl analogs of these three sterols. The three mutants had altered sterol composition, but none required exogenous sterol for growth. KD7 contained a C28-5,7,22,25-tetraene, a C28-5,7,25-triene, a C28-7,25-diene, and three C-24 ethyl analogs. The lesion in KD7 is apparently an inability to reduce the C-25 double bond required for the biosynthesis of ergosterol and an ethyl analog. The predominant sterols accumulated by KD16 and KD21 were a C28-5,7-diene, a C28-7-ene, and C-24 ethyl versions of these two sterols, suggesting that these strains are 22(23)-desaturase mutants.

Enhancement of kinase selectivity in a potent class of arylamide FMS inhibitors

Structure-activity relationship (SAR) studies on a highly potent series of arylamide FMS inhibitors were carried out with the aim of improving FMS kinase selectivity, particularly over KIT. Potent compound 17r (FMS IC50 0.7 nM, FMS cell IC50 6.1 nM) was discovered that had good PK properties and a greater than fivefold improvement in selectivity for FMS over KIT kinase in a cellular assay relative to the previously reported clinical candidate 4. This improved selectivity was manifested in vivo by no observed decrease in circulating reticulocytes, a measure of bone safety, at the highest studied dose. Compound 17r was highly active in a mouse pharmacodynamic model and demonstrated disease-modifying effects in a dose-dependent manner in a strep cell wall-induced arthritis model of rheumatoid arthritis in rats.

Engineering the interface between glucose oxidase and nanoparticles

The behavior of glucose oxidase (GOx) on gold nanoparticles (NPs) was investigated as a function of (1) NP surface chemistry, (2) stabilizing protein additives, and (3) protein microenvironment. GOx secondary structure and unfolding was probed by circular dichroism (CD) spectroscopy and fluorescence, and GOx enzymatic activity was measured by a colorimetric assay. We also examined the activity and structure of GOx after displacement from the NP surface. Generally, GOx behavior was negatively impacted by conjugation to the NP, and conjugation conditions could vary the influence of the NP. Surface chemistry and protein microenvironment could improve behavior, but addition of stabilizing proteins negatively influenced activity. After displacement from the NPs, GOx tended to remain unfolded, indicating that the interactions with the NP were irreversible.

Diversity of Rhizobia Nodulating Phaseolus vulgaris L. in Two Kenyan Soils with Contrasting pHs

Rhizobia were isolated from two Kenyan soils with pHs of 4.5 and 6.8 and characterized on the basis of their host ranges for nodulation and nitrogen fixation, colony morphologies, restriction fragment fingerprints, and hybridization with a nifH probe. The populations of rhizobia nodulating Phaseolus vulgaris in the two soils were similar in numbers and in effectiveness of N(inf2) fixation but were markedly different in composition. The population in the Naivasha soil (pH 6.8) was dominated by isolates specific in host range for nodulation to P. vulgaris; these all had multiple copies, in most cases four, of the structural nitrogenase gene nifH. Only one of the isolates from this soil formed effective nodules on Leucaena leucocephala, and this isolate had only a single copy of nifH. By contrast, the population in the acid Daka-ini soil (pH 4.5) was composed largely of broad-host-range isolates which had single copies of nifH. The isolates from the Daka-ini soil which were specific to P. vulgaris generally had three copies of nifH, although one isolate had only two copies. These rhizobial isolates are indigenous to Kenyan soils and yet have marked similarities to previously described Rhizobium species from other continents.

JNJ-28312141, a novel orally active colony-stimulating factor-1 receptor/FMS-related receptor tyrosine kinase-3 receptor tyrosine kinase inhibitor with potential utility in solid tumors, bone metastases, and acute myeloid leukemia

There is increasing evidence that tumor-associated macrophages promote the malignancy of some cancers. Colony-stimulating factor-1 (CSF-1) is expressed by many tumors and is a growth factor for macrophages and mediates osteoclast differentiation. Herein, we report the efficacy of a novel orally active CSF-1 receptor (CSF-1R) kinase inhibitor, JNJ-28312141, in proof of concept studies of solid tumor growth and tumor-induced bone erosion. H460 lung adenocarcinoma cells did not express CSF-1R and were not growth inhibited by JNJ-28312141 in vitro. Nevertheless, daily p.o. administration of JNJ-28312141 caused dose-dependent suppression of H460 tumor growth in nude mice that correlated with marked reductions in F4/80(+) tumor-associated macrophages and with increased plasma CSF-1, a possible biomarker of CSF-1R inhibition. Furthermore, the tumor microvasculature was reduced in JNJ-28312141-treated mice, consistent with a role for macrophages in tumor angiogenesis. In separate studies, JNJ-28312141 was compared with zoledronate in a model in which MRMT-1 mammary carcinoma cells inoculated into the tibias of rats led to severe cortical and trabecular bone lesions. Both agents reduced tumor growth and preserved bone. However, JNJ-28312141 reduced the number of tumor-associated osteoclasts superior to zoledronate. JNJ-28312141 exhibited additional activity against FMS-related receptor tyrosine kinase-3 (FLT3). To more fully define the therapeutic potential of this new agent, JNJ-28312141 was evaluated in a FLT3-dependent acute myeloid leukemia tumor xenograft model and caused tumor regression. In summary, this novel CSF-1R/FLT3 inhibitor represents a new agent with potential therapeutic activity in acute myeloid leukemia and in settings where CSF-1-dependent macrophages and osteoclasts contribute to tumor growth and skeletal events.

Development of polymorphic expressed sequence tag-derived microsatellites for the extension of the genetic linkage map of the black tiger shrimp (Penaeus monodon)

In this study, microsatellite markers were developed for the genetic linkage mapping and breeding program of the black tiger shrimp Penaeus monodon. A total of 997 unique microsatellite-containing expressed sequence tags (ESTs) were identified from 10 100 EST sequences in the P. monodon EST database. AT-rich microsatellite types were predominant in the EST sequences. Homology searching by the blastn and blastx programs revealed that these 997 ESTs represented 8.6% known gene products, 27.8% hypothetical proteins and 63.6% unknown gene products. Characterization of 50 markers on a panel of 35-48 unrelated shrimp indicated an average number of alleles of 12.6 and an average polymorphic information content of 0.723. These EST microsatellite markers along with 208 other markers (185 amplified fragment length polymorphisms, one exon-primed intron-crossing, six single strand conformation polymorphisms, one single nucleotide polymorphism, 13 non-EST-associated microsatellites and two EST-associated microsatellites) were analysed across the international P. monodon mapping family. A total of 144 new markers were added to the P. monodon maps, including 36 of the microsatellite-containing ESTs. The current P. monodon male and female linkage maps have 47 and 36 linkage groups respectively with coverage across half the P. monodon genome.

Predictors for non-adherence to antiretroviral therapy

Objectives: To determine the risk factors for non-adherence to antiretroviral therapy. Methods: Two hundred clients attending the Melbourne Sexual Health Centre completed a questionnaire about lifestyle, self-efficacy, depression, drug or alcohol use, social supports, and attitudes to health care. Self-reported adherence (SRA) was measured by missed doses in the last 4, 7 and 28 days. Routinely collected viral load levels were reviewed. Results: Two hundred (85%) out of 231 eligible clients participated in the study. Viral load was most strongly associated with SRA for the last 28 days (P < 0.001). Non-adherence was defined as <98.2% SRA. Non-adherence was most strongly associated with having regular daily routines [odds ratio and 95% confidence interval = 0.4 (0.2, 0.7], having set times for getting up and going to bed [0.5 (0.3, 1.0)], using marijuana more than 4 times per week [0.4 (0.2, 1.0)] and lower self-efficacy which included; being sure that you will be able to take medications as directed [0.2 (0.1, 0.6)] and being sure that missing doses of HIV medication will result in drug resistance [0.4 (0.2, 0.7)]. When significant questions were combined into a composite score to screen for non-adherence, the sensitivity to predict non-adherence was as high as 71% with a specificity of 59%. Conclusions : This study showed that a 10-min questionnaire was associated with clients past non-adherence to antiretroviral therapy and may be useful for predicting future adherence.

Design and synthesis of 4,5-disubstituted-thiophene-2-amidines as potent urokinase inhibitors

A study of the S1 binding of lead 5-methylthiothiophene amidine 3, an inhibitor of urokinase-type plasminogen activator, was undertaken by the introduction of a variety of substituents at the thiophene 5-position. The 5-alkyl substituted and unsubstituted thiophenes were prepared using organolithium chemistry. Heteroatom substituents were introduced at the 5-position using a novel displacement reaction of 5-methylsulfonylthiophenes and the corresponding oxygen or sulfur anions. Small alkyl group substitution at the 5-position provided inhibitors equipotent with but possessing improved solubility.

Structure-Based design, synthesis and sAR of a novel series of thiopheneamidine urokinase plasminogen activator inhibitors

The serine protease urokinase plasminogen activator (uPA) is thought to play a central role in tumor metastasis and angiogenesis. Molecular modeling studies suggest that 5-thiomethylthiopheneamidine inhibits uPA by binding at the S1 pocket of the active site. Further structure based elaboration of this residue resulted in a novel class of potent and selective inhibitors of uPA.

Synthesis of thiophene-2-carboxamidines containing 2-aminothiazoles and their biological evaluation as urokinase inhibitors

The serine protease urokinase (uPa) has been implicated in the progression of both breast and prostate cancer. Utilizing structure based design, the synthesis of a series of substituted 4-[2-amino-1,3-thiazolyl]-thiophene-2-carboxamidines is described. Further optimization of this series by substitution of the terminal amine yielded urokinase inhibitors with excellent activities.

Research and development to improve naval shipboard waste management using a compact closed-loop-controlled waste incinerator

Research has been conducted into the application of forced acoustics for enhancing the performance of a pyrolyzed waste afterburner configured as a dump combustor. Subscale studies showed that acoustic forcing of an air jet entering a dump chamber could trigger the formation of coherent vortices generated by entrainment of ambient gases. Subsequent studies showed that combustible gases could be introduced into the coherent vortices, and with additional modulation this configuration would lead to an enhanced combustion rate with low emissions of pollutants. The acoustically forced burner concept was scaled up to practical levels and tested as an afterburner on a commercial waste incinerator operating in pyrolysis mode. Results show that the afterburner can promote both compactness, due to the rapid combustion rate, and low pollutant emissions resulting from enhanced mixing prior to combustion.

Phylogenetic diversity of bacteria associated with the marine sponge Rhopaloeides odorabile

Molecular techniques were employed to document the microbial diversity associated with the marine sponge Rhopaloeides odorabile. The phylogenetic affiliation of sponge-associated bacteria was assessed by 16S rRNA sequencing of cloned DNA fragments. Fluorescence in situ hybridization (FISH) was used to confirm the presence of the predominant groups indicated by 16S rDNA analysis. The community structure was extremely diverse with representatives of the Actinobacteria, low-G+C gram-positive bacteria, the beta- and gamma-subdivisions of the Proteobacteria, Cytophaga/Flavobacterium, green sulfur bacteria, green nonsulfur bacteria, planctomycetes, and other sequence types with no known close relatives. FISH probes revealed the spatial location of these bacteria within the sponge tissue, in some cases suggesting possible symbiotic functions. The high proportion of 16S rRNA sequences derived from novel actinomycetes is good evidence for the presence of an indigenous marine actinomycete assemblage in R. odorabile. High microbial diversity was inferred from low duplication of clones in a library with 70 representatives. Determining the phylogenetic affiliation of sponge-associated microorganisms by 16S rRNA analysis facilitated the rational selection of culture media and isolation conditions to target specific groups of well-represented bacteria for laboratory culture. Novel media incorporating sponge extracts were used to isolate bacteria not previously recovered from this sponge.

Five Crustacean Hyperglycemic Family Hormones of Penaeus monodon: Complementary DNA Sequence and Identification in Single Sinus Glands by Electrospray Ionization-Fourier Transform Mass Spectrometry

Five novel neuropeptides, designated Pm-sgp-I to -V, of the crustacean hyperglycemic hormone (CHH) family have been identified from the giant tiger prawn Penaeus monodon by isolation of the preprohormone genes from an eyestalk complementary DNA library. On the basis of sequence similarity, the encoded peptides have been classified as CHH-like type I hormones, which include all known CHHs and the molt-inhibiting hormone (MIH) of the lobster Homarus americanus. Consistent with CHH type I preprohormones, the Pm-sgp precursors include a signal peptide, a CHH precursor-related peptide (CPRP), and the CHH-like hormone. Analysis by electrospray ionization-Fourier transform mass spectrometry enabled the neuropeptide complement of individual sinus glands to be resolved. It also confirmed the presence of the five Pm-sgp neuropeptides within the sinus gland of an individual animal, in that the masses observed were consistent with those predicted from the gene sequence of the Pm-sgps after posttranslational modification. These modifications included cleavage of the signal peptide and precursor protein, carboxy-terminal amidation, and formation of three disulfide bridges. Analysis of crude extracts of single sinus glands from different animals revealed variation in neuropeptide content and will provide a tool for determining whether the content varies as a function of the physiological state of the animal.

Tissue-Specific Expressed Sequence Tags from the Black Tiger Shrimp Penaeus monodon

: Expressed sequence tag data were generated from complementary DNA libraries created from cephalothorax, eyestalk, and pleopod tissue of the black tiger shrimp (Penaeus monodon). Significant database matches were found for 48 of 83 nuclear genes sequenced from the cephalothorax library, 22 of 55 nuclear genes from the eyestalk library, and 6 of 13 nuclear genes from the pleopod library. The putative identities of these genes reflected the expected tissue specificity. For example, genes for digestive enzymes were identified from the cephalothorax library and genes involved in the visual and neuroendocrine system from the eyestalk library. A few sequences matched anonymous EST or genomic sequences, and others contained mini-satellite or microsatellite repeat sequences. The remainder, 31 from the cephalothorax library, 25 from the eyestalk library, and 5 from the pleopod library, were sequences of high nucleotide complexity with no matches in any database searched and thus may represent novel genes.

Prediction of peptide affinity to HLA DR molecules

A method to quantitatively predict peptide binding to HLA DRB1*0401, B1*0101, and B1*1501 has been developed using a dataset of the relative contributions of each of the naturally occurring amino acids in the context of a simplified peptide backbone. The prediction assumed that the relative role of each of the peptide sidechains could be treated independently and could be measured by assaying each of the twenty naturally occurring amino acids at the central eleven positions of a 13 residue peptide previously shown to contain the minimal requirements for high affinity binding to HLA DR proteins. Three separate databases were generated. They were shown to have predictive value when tested on a set of 13 unrelated peptides known to bind the DR proteins with a wide range of apparent affinity. The DRB1*0401 database was tested further by analyzing myelin basic protein. All 13 amino acid peptides containing a hydrophobic amino acid at the third position were synthesized and assayed for binding purified DRB1*0401. In every case, the measured affinity correlated with the predictive values within the experimental error of the assays. Finally, the ability to predict peptide binding to MHC class II molecules was shown to help in identifying T cell determinants. The specificity of DRB1*0401 restricted T cell hybridomas against human serum albumin corresponded to two peptides, predicted, and shown to bind the class II protein with high affinity.

Down-regulation of poison ivy/oak-induced contact sensitivity by treatment with a class II MHC binding peptide:hapten conjugate

Immune regulation of contact sensitivity to the poison ivy/oak catechol was studied at the level of class II MHC-restricted T cell recognition of hapten:peptide conjugates. In this study we have shown that 1) T cells from C3H/HeN (H-2k) mice, immunized with a synthetic I-Ak binding peptide coupled to 3-pentadecyl-catechol (PDC; a representative catechol in urushiol), recognized peptides derived from syngeneic cells linked to the same catechol; 2) T cells from draining lymph nodes of C3H/HeN mice skin-painted with PDC proliferated in response to a peptide carrier:PDC conjugate only when it was linked at the 7th, but not the 4th or the 10th, position on the peptide carrier; and 3) tolerization studies confirmed down-regulation of PDC-induced delayed-type hypersensitivity following treatment with a single I-Ak binding peptide carrying PDC covalently bound to a lysine residue at the middle (7th) TCR contact position. Tolerization with peptide:PDC conjugate resulted in abrogation of hapten-specific T cell proliferative responses that correlated with diminished IL-2 secretion. On the basis of these data we propose that it may be sufficient to couple the hapten at a single, well-chosen position on a carrier peptide to target a relevant population of T cells involved in contact sensitivity.

Effect of ovariectomy and steroid hormone replacement on the recovery of arterial blood pressure following haemorrhage in anaesthetized Brattleboro rats

There is increasing evidence that ovarian steroids inhibit vascular responsiveness to the neurohypophysial hormone vasopressin. The present study examined the recovery of the arterial blood pressure following a single (2 ml/100 g body weight) haemorrhage in ovariectomized (OVX) Brattleboro rats with hereditary hypothalamic diabetes insipidus (BDI) and rats of the parent Long Evans (LE) strain. Some groups of OVX rats received subcutaneous implants of either 17 beta-oestradiol (E2) or progesterone 7 days prior to haemorrhage. The arterial blood pressure recovery immediately following haemorrhage was significantly impaired in both groups of steroid-treated OVX LE rats compared with the OVX controls (both comparisons P < 0.05). The impairment in blood pressure recovery seen in the steroid-replaced OVX LE rats was similar to that seen in pro-oestrous rats (when ovarian steroid levels are raised) compared with male rats of this strain (P < 0.05). In contrast, ovariectomy with or without steroid replacement in BDI rats had no further effect on the already attenuated recovery of arterial blood pressure after haemorrhage in this strain. Heart rate responses to haemorrhage also showed strain differences, which were dependent on steroid treatment. Pro-oestrous female LE rats showed a small decrease in heart rate after haemorrhage, followed by a recovery process, and this initial bradycardia was markedly enhanced in the OVX steroid-treated animals. In contrast, untreated OVX LE rats showed an initial and sustained increase in heart rate which was significantly higher than in the steroid-treated OVX animals (P < 0.05). All BDI rats, irrespective of treatment, consistently showed an increased heart rate after haemorrhage. In conclusion, ovarian steroid replacement in OVX LE, but not vasopressin-deficient BDI, rats was associated with an attenuated pressor recovery after haemorrhage. This provides further evidence for the existence of an important inhibitory interaction between ovarian steroids and vasopressin. The initial decrease in heart rate observed in pro-oestrous and steroid-treated OVX LE rats after haemorrhage also appears to be related to an ovarian steroid-vasopressin interaction.

Down-regulation of poison ivy/oak-induced contact sensitivity by treatment with a class II MHC binding peptide:hapten conjugate

Immune regulation of contact sensitivity to the poison ivy/oak catechol was studied at the level of class II MHC-restricted T cell recognition of hapten:peptide conjugates. In this study we have shown that 1) T cells from C3H/HeN (H-2k) mice, immunized with a synthetic I-Ak binding peptide coupled to 3-pentadecyl-catechol (PDC; a representative catechol in urushiol), recognized peptides derived from syngeneic cells linked to the same catechol; 2) T cells from draining lymph nodes of C3H/HeN mice skin-painted with PDC proliferated in response to a peptide carrier:PDC conjugate only when it was linked at the 7th, but not the 4th or the 10th, position on the peptide carrier; and 3) tolerization studies confirmed down-regulation of PDC-induced delayed-type hypersensitivity following treatment with a single I-Ak binding peptide carrying PDC covalently bound to a lysine residue at the middle (7th) TCR contact position. Tolerization with peptide:PDC conjugate resulted in abrogation of hapten-specific T cell proliferative responses that correlated with diminished IL-2 secretion. On the basis of these data we propose that it may be sufficient to couple the hapten at a single, well-chosen position on a carrier peptide to target a relevant population of T cells involved in contact sensitivity.

Simultaneous detection of different Rhizobium strains marked with either the Escherichia coli gusA gene or the Pyrococcus furiosus celB gene

A new marker system for gram-negative bacteria was developed on the basis of the celB gene from the hyperthermophilic archaeon Pyrococcus furiosus, which encodes a thermostable beta-glucosidase with a high level of beta-galactosidase activity. The celB gene is highly suitable as a marker for studying plant-bacterium interaction because endogenous background beta-glucosidase and beta-galactosidase enzyme activity can readily be inactivated by heat and because inexpensive substrates for detection are commercially available. Two celB-expressing transposons were constructed for use in ecological studies of a variety of gram-negative bacteria. The combined use of the gusA marker gene and celB allowed the simultaneous detection of several Rhizobium strains on a plant, and multiple-strain occupancy of individual modules also could be easily detected.

Differential stability of HLA-DR alleles independent of endogenous peptides

Purified HLA DRB1*0101 was shown to be inherently more stable to dissociation than DRB1*0401. The residues responsible for the differential stability were defined by constructing hybrid molecules, which contained a small number of residues from DRB1*0101 substituted into the framework of DRB1*0401. One of the hybrid molecules, containing six substituted amino acids, was as stable as DRB1*0101, but exhibited the binding specificity of DRB1*0401. This result indicated that the differential stability between the alleles arose from structural differences, and was not due solely to varying populations of endogenous peptides.

Differential stability of HLA-DR alleles independent of endogenous peptides

Purified HLA DRB1*0101 was shown to be inherently more stable to dissociation than DRB1*0401. The residues responsible for the differential stability were defined by constructing hybrid molecules, which contained a small number of residues from DRB1*0101 substituted into the framework of DRB1*0401. One of the hybrid molecules, containing six substituted amino acids, was as stable as DRB1*0101, but exhibited the binding specificity of DRB1*0401. This result indicated that the differential stability between the alleles arose from structural differences, and was not due solely to varying populations of endogenous peptides.

beta-Glucuronidase (GUS) transposons for ecological and genetic studies of rhizobia and other gram-negative bacteria

A series of transposons are described which contain the gusA gene, encoding beta-glucuronidase (GUS), expressed from a variety of promoters, both regulated and constitutive. The regulated promoters include the tac promoter which can be induced by IPTG, and nifH promoters which are symbiotically activated in legume nodules. One transposon contains gusA with a strong Shine-Dalgarno translation initiation context, but no promoter, and thus acts as a promoter-probe transposon. In addition, a gus operon deletion strain of Escherichia coli, and a transposon designed for use in chromosomal mapping using PFGE, are described. The GUS transposons are constructed in a mini-Tn5 system which can be transferred to Gram-negative bacteria by conjugation, and will form stable genomic insertions. Due to the absence of GUS activity in plants and many bacteria of economic importance, these transposons constitute powerful new tools for studying the ecology and population biology of bacteria in the environment and in association with plants, as well as for studies of the fundamental molecular basis of such interactions. The variety of assays available for GUS enable both quantitative assays and spatial localization of marked bacteria to be carried out.

Prediction of peptide affinity to HLA DRB1*0401

A method to predict quantitatively peptide binding to HLA DRB1*0401 has been developed using a data set of the relative contributions of each of the naturally occurring amino acids in the context of a simplified peptide back-bone. The prediction assumed that the relative role of each of the peptide side chains could be treated independently and could be measured by assaying each of the 20 naturally occurring amino acids at the central 11 positions of a 13-residue peptide previously shown to contain the minimal requirements for high-affinity binding to HLA-DR proteins. The resultant database was shown to have predictive value when tested on a set of 13 unrelated peptides known to bind DRB1*0401 with a wide range of apparent affinity. The database was tested further by analyzing myelin basic protein. All 13 amino acid peptides containing a hydrophobic amino acid at the third position were synthesized and assayed for binding purified DRB1*0401. In every case, the measured affinity correlated with the predictive values within the experimental error of the assays. Finally, the ability to predict peptide binding to MHC class II molecules was shown to help in identifying T cell determinants. The specificity of DRB1*0401-restricted T cell hybridomas against human serum albumin corresponded to two peptides, predicted and shown to bind the class II protein with high affinity.

Prediction of peptide affinity to HLA DRB1*0401

A method to predict quantitatively peptide binding to HLA DRB1*0401 has been developed using a data set of the relative contributions of each of the naturally occurring amino acids in the context of a simplified peptide back-bone. The prediction assumed that the relative role of each of the peptide side chains could be treated independently and could be measured by assaying each of the 20 naturally occurring amino acids at the central 11 positions of a 13-residue peptide previously shown to contain the minimal requirements for high-affinity binding to HLA-DR proteins. The resultant database was shown to have predictive value when tested on a set of 13 unrelated peptides known to bind DRB1*0401 with a wide range of apparent affinity. The database was tested further by analyzing myelin basic protein. All 13 amino acid peptides containing a hydrophobic amino acid at the third position were synthesized and assayed for binding purified DRB1*0401. In every case, the measured affinity correlated with the predictive values within the experimental error of the assays. Finally, the ability to predict peptide binding to MHC class II molecules was shown to help in identifying T cell determinants. The specificity of DRB1*0401-restricted T cell hybridomas against human serum albumin corresponded to two peptides, predicted and shown to bind the class II protein with high affinity.

Specific T cell recognition of minimally homologous peptides: evidence for multiple endogenous ligands

The T cell receptor (TCR) can interact with a spectrum of peptides as part of its ligand, including the immunogenic peptide, variants of this peptide,and apparently unrelated peptides. The basis of this broad specificity for ligand was investigated by substitution analysis of a peptide antigen and functional testing using a B cell apoptosis assay. A peptide containing as few as 1 aa in common with this peptide could stimulate a specific T cell response. Two endogenous ligands, an agonist and a partial agonist, were readily identified from a search of the SwissProt database, indicating that multiple endogenous ligands likely exist for a given T cell. These findings strongly support the concept that one TCR has the ability to interact productively with multiple different ligands, and provide evidence that such ligands exist in the endogenous peptide repertoire.