Inhibitory mechanism of an allosteric antibody targeting the glucagon receptor.

Elevated glucagon levels and increased hepatic glucagon receptor (GCGR) signaling contribute to hyperglycemia in type 2 diabetes. We have identified a monoclonal antibody that inhibits GCGR, a class B G-protein coupled receptor (GPCR), through a unique allosteric mechanism. Receptor inhibition is mediated by the binding of this antibody to two distinct sites that lie outside of the glucagon binding cleft. One site consists of a patch of residues that are surface-exposed on the face of the extracellular domain (ECD) opposite the ligand-binding cleft, whereas the second binding site consists of residues in the αA helix of the ECD. A docking model suggests that the antibody does not occlude the ligand-binding cleft. We solved the crystal structure of GCGR ECD containing a naturally occurring G40S mutation and found a shift in the register of the αA helix that prevents antibody binding. We also found that alterations in the αA helix impact the normal function of GCGR. We present a model for the allosteric inhibition of GCGR by a monoclonal antibody that may form the basis for the development of allosteric modulators for the treatment of diabetes and other class B GPCR-related diseases.

A rare case of straight-back syndrome causing airway obstruction.

Straight-back syndrome is a rare congenital condition involving the loss of the normal dorsal curvature of the upper thoracic spine. This leads to flattening of the upper thoracic cavity, resulting in compression of the underlying vasculature and airways. In this case report, we discuss the management of an 18-year-old male with straight-back syndrome who was referred to our interventional pulmonary clinic for further management of his stridor and apneic events. A trial of airway stenting was done which resolved the patient's respiratory symptoms. Definitive surgical correction was not applicable due to other significant medical conditions, but tracheostomy provided a sustainable alternative treatment. Tracheostomy tube placement and airway stenting are reasonable alternatives to surgery for patients who experience airway obstruction due to straight-back syndrome. Stent placement may also relieve respiratory symptoms but is associated with a higher rate of complications.

Quantitative analysis of spin exchange interactions to identify ß strand and turn regions in Ure2 prion domain fibrils with site-directed spin labeling.

Amyloid formation is associated with a range of debilitating human disorders including Alzheimer's and prion diseases. The amyloid structure is essential for understanding the role of amyloids in these diseases. Amyloid formation of Ure2 protein underlies the yeast prion [URE3]. Here we use site-directed spin labeling and electron paramagnetic resonance (EPR) spectroscopy to investigate the structure of amyloid fibrils formed by the Ure2 prion domain. The Ure2 prion domain under study contains a Sup35M domain at C-terminus as a solubilization element. We introduced spin labels at every residue from positions 2-15, and every 5th residue from positions 20-80 in Ure2 prion domain. EPR spectra at most labeling sites show strong spin exchange interactions, suggesting a parallel in-register ß structure. With quantitative analysis of spin exchange interactions, we show that residues 8-12 form the first ß strand, followed by a turn at residues 13-14, and then the second ß strand from residue 15 to at least residue 20. Comparison of the spin exchange frequency for the fibrils formed under quiescent and agitated conditions also revealed differences in the fibril structures. Currently there is a lack of techniques for in-depth structural studies of amyloid fibrils. Detailed structural information is obtained almost exclusively from solid-state NMR. The identification of ß-strand and turn regions in this work suggests that quantitative analysis of spin exchange interactions in spin-labeled amyloid fibrils is a powerful approach for identifying the ß-strand and turn/loop residues and for studying structural differences of different fibril polymorphs.

Childbearing is associated with higher incidence of the metabolic syndrome among women of reproductive age controlling for measurements before pregnancy: the CARDIA study.

OBJECTIVE: We sought to prospectively examine whether childbearing is associated with higher incidence of the metabolic syndrome (MetS) after delivery among women of reproductive age. STUDY DESIGN: In 1451 nulliparas who were aged 18-30 years and free of the MetS at baseline (1985-1986) and reexamined up to 4 times during 20 years, we ascertained incident MetS defined by the National Cholesterol Education Program Adult Treatment Panel III criteria among time-dependent interim birth groups by gestational diabetes mellitus (GDM): (0 [referent], 1 non-GDM, 2+ non-GDM, 1+ GDM births). Complementary log-log models estimated relative hazards of the MetS among birth groups adjusted for race, age, and baseline and follow-up covariates. RESULTS: We identified 259 incident MetS cases in 25,246 person-years (10.3/1000 person-years). Compared with 0 births, adjusted relative hazards (95% confidence interval [CI]) were 1.33 (95% CI, 0.93-1.90) for 1 non-GDM, 1.62 (95% CI, 1.16-2.26) for 2+ non-GDM (P trend = .02), and 2.43 (95% CI, 1.53-3.86) for 1+ GDM births. CONCLUSION: Increasing parity is associated with future development of the MetS independent of prior obesity and pregnancy-related weight gain. Risk varies by GDM status.

Long-term blood pressure changes measured from before to after pregnancy relative to nonparous women.

OBJECTIVE: To prospectively examine whether blood pressure changes persist after pregnancy among women of reproductive age. METHODS: This was a prospective, population-based, observational cohort of 2,304 (1,167 black, 1,137 white) women (aged 18-30 years) who were free of hypertension at baseline (1985-1986) and reexamined up to six times at 2, 5, 7, 10, or 20 years later (2005-2006). We obtained standardized blood pressure measurements before and after pregnancies and categorized women into time-dependent groups by the cumulative number of births since baseline within each time interval (zero births [referent]; one interim birth and two or more interim births; nonhypertensive pregnancies). The study assessed differences in systolic and diastolic blood pressures among interim birth groups using multivariable, repeated measures linear regression models stratified by baseline parity (nulliparous and parous), adjusted for time, age, race, baseline covariates (blood pressure, body mass index, education, and oral contraceptive use), and follow-up covariates (smoking, antihypertensive medications, oral contraceptive use, and weight gain). RESULTS: Among nulliparas at baseline, mean (95% confidence interval) fully adjusted systolic and diastolic blood pressures (mm Hg), respectively, were lower by -2.06 (-2.72 to -1.41) and -1.50 (-2.08 to -0.92) after one interim birth, and lower by -1.89 (-2.63 to -1.15) and -1.29 (-1.96 to -0.63) after two or more interim births compared with no births (all P<.001). Among women already parous at baseline, adjusted mean blood pressure changes did not differ by number of subsequent births. CONCLUSION: A first birth is accompanied by persistent lowering of blood pressure from preconception to years after delivery. Although the biologic mechanism is unclear, pregnancy may create enduring alterations in vascular endothelial function. LEVEL OF EVIDENCE: II.

Postoperative Complications for Elderly Patients After Single-Level Lumbar Fusions for Spondylolisthesis.

OBJECTIVE: A large-scale study on postoperative complications of lumbar fusion surgery for spondylolisthesis comparing patients >80 years old with younger patients has not been performed. The purpose of this study is to assess the effects of extreme age (>80 years old) on early postoperative outcomes after single-level lumbar fusions for spondylolisthesis. METHODS: From a validated multicenter surgical database, 2475 patients who underwent a single-level lumbar fusion procedure for spondylolisthesis were selected retrospectively. An extreme age cohort with 227 patients >80 years old was compared with a typical age cohort with 2248 patients 45-65 years old. RESULTS: The preoperative characteristics and comorbidities were different between the typical age cohort and the extreme age cohort, with older patients having more preoperative comorbidities, including a lack of independent functional health status before surgery (P < 0.001), severe chronic obstructive pulmonary disease (P <0.020), and hypertension requiring medication (P < 0.001). There was significantly greater morbidity among the >80 cohort regarding urinary tract infection (P = 0.008; odds ratio = 3.30; 95% confidence interval, 1.47-7.40) and intraoperative and postoperative transfusions (P < 0.001; odds ratio = 2.186; 95% confidence interval, 1.54-3.11). There was significantly greater morbidity among the younger cohort regarding cardiac arrest requiring cardiopulmonary resuscitation (P = 0.043; odds ratio = 0.099; 95% confidence interval, 0.014-0.704). CONCLUSIONS: This is the first large study comparing the rates of postoperative complications of lumbar fusion surgery for spondylolisthesis in patients >80 years old versus younger patients. The data support that age alone should not exclude a patient for this procedure. However, extra caution is warranted given the slightly increased morbidity.

History of gestational diabetes mellitus and future risk of atherosclerosis in mid-life: the Coronary Artery Risk Development in Young Adults study.

BACKGROUND: History of gestational diabetes mellitus (GDM) increases lifetime risk of type 2 diabetes (DM) and the metabolic syndrome (MetS), which increase risk of cardiovascular disease. It is unclear, however, whether GDM increases risk of early atherosclerosis independent of pre-pregnancy obesity and subsequent metabolic disease. METHODS AND RESULTS: Of 2787 women (18 to 30 years) enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study, we studied 898 (47% black) who were free of DM and heart disease at baseline (1985-1986), delivered ≥1 post-baseline births, reported GDM history, and had common carotid intima media thickness (ccIMT, mm) measured in 2005-2006. We used multivariable linear regression to assess associations between GDM and ccIMT adjusted for race, age, parity, and pre-pregnancy cardiometabolic risk factors. We assessed mediators (weight gain, insulin resistance, blood pressure), and effect modification by incident DM or MetS during the 20-year period. Of the 898 women, 119 (13%) reported GDM (7.6 per 100 deliveries). Average age was 31 at last birth and 44 at ccIMT measurement for GDM and non-GDM groups. Unadjusted mean ccIMT was 0.023 mm higher for GDM than non-GDM groups (P=0.029), but pre-pregnancy BMI attenuated the difference to 0.016 mm (P=0.109). In 777 women without subsequent DM or the MetS, mean ccIMT was 0.023 mm higher for GDM versus non-GDM groups controlling for race, age, parity, and pre-pregnancy BMI (0.784 versus 0.761, P=0.039). Addition of pre-pregnancy insulin resistance index had minimal impact on adjusted mean net ccIMT difference (0.22 mm). Mean ccIMT did not differ by GDM status among 121 women who developed DM or the MetS (P=0.58). CONCLUSIONS: History of GDM may be a marker for early atherosclerosis independent of pre-pregnancy obesity among women who have not developed type 2 diabetes or the metabolic syndrome.

Prion domain of yeast Ure2 protein adopts a completely disordered structure: a solid-support EPR study.

Amyloid fibril formation is associated with a range of neurodegenerative diseases in humans, including Alzheimer's, Parkinson's, and prion diseases. In yeast, amyloid underlies several non-Mendelian phenotypes referred to as yeast prions. Mechanism of amyloid formation is critical for a complete understanding of the yeast prion phenomenon and human amyloid-related diseases. Ure2 protein is the basis of yeast prion [URE3]. The Ure2p prion domain is largely disordered. Residual structures, if any, in the disordered region may play an important role in the aggregation process. Studies of Ure2p prion domain are complicated by its high aggregation propensity, which results in a mixture of monomer and aggregates in solution. Previously we have developed a solid-support electron paramagnetic resonance (EPR) approach to address this problem and have identified a structured state for the Alzheimer's amyloid-ß monomer. Here we use solid-support EPR to study the structure of Ure2p prion domain. EPR spectra of Ure2p prion domain with spin labels at every fifth residue from position 10 to position 75 show similar residue mobility profile for denaturing and native buffers after accounting for the effect of solution viscosity. These results suggest that Ure2p prion domain adopts a completely disordered structure in the native buffer. A completely disordered Ure2p prion domain implies that the amyloid formation of Ure2p, and likely other Q/N-rich yeast prion proteins, is primarily driven by inter-molecular interactions.

Lactation intensity and postpartum maternal glucose tolerance and insulin resistance in women with recent GDM: the SWIFT cohort.

OBJECTIVE: To examine the association between breastfeeding intensity in relation to maternal blood glucose and insulin and glucose intolerance based on the postpartum 2-h 75-g oral glucose tolerance test (OGTT) results at 6-9 weeks after a pregnancy with gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: We selected 522 participants enrolled into the Study of Women, Infant Feeding, and Type 2 Diabetes (SWIFT), a prospective observational cohort study of Kaiser Permanente Northern California members diagnosed with GDM using the 3-h 100-g OGTT by the Carpenter and Coustan criteria. Women were classified as normal, prediabetes, or diabetes according to American Diabetes Association criteria based on the postpartum 2-h 75-g OGTT results. RESULTS: Compared with exclusive or mostly formula feeding (>17 oz formula per 24 h), exclusive breastfeeding and mostly breastfeeding (≤6 oz formula per 24 h) groups, respectively, had lower adjusted mean (95% CI) group differences in fasting plasma glucose (mg/dL) of -4.3 (-7.4 to -1.3) and -5.0 (-8.5 to -1.4), in fasting insulin (µU/mL) of -6.3 (-10.1 to -2.4) and -7.5 (-11.9 to -3.0), and in 2-h insulin of -21.4 (-41.0 to -1.7) and -36.5 (-59.3 to -13.7) (all P < 0.05). Exclusive or mostly breastfeeding groups had lower prevalence of diabetes or prediabetes (P = 0.02). CONCLUSIONS: Higher intensity of lactation was associated with improved fasting glucose and lower insulin levels at 6-9 weeks' postpartum. Lactation may have favorable effects on glucose metabolism and insulin sensitivity that may reduce diabetes risk after GDM pregnancy.

Influence of breastfeeding during the postpartum oral glucose tolerance test on plasma glucose and insulin.

OBJECTIVE: To examine the effect of breastfeeding during the postpartum oral glucose tolerance test (OGTT) on maternal blood glucose and insulin among women with recent gestational diabetes mellitus. METHODS: Participants were enrolled in the Study of Women, Infant Feeding, and Type 2 Diabetes, a prospective observational cohort study of 1,035 Kaiser Permanente Northern California members who had been diagnosed with GDM and subsequently underwent a 2-hour 75-g OGTT at 6-9 weeks postpartum for the study enrollment examinations from 2008 to 2011. For this analysis, we selected 835 study participants who reported any intensity of lactation and were observed either breastfeeding their infants (ie, putting the infant to the breast) or not breastfeeding during the OGTT. RESULTS: Of 835 lactating women, 205 (25%) breastfed their infants during the 2-hour 75-g OGTT at 6-9 weeks postpartum. Mean (standard deviation) duration of breastfeeding during the OGTT was 15.3 (8.1) minutes. Compared with not having breastfed during the OGTT, having breastfed during the test was associated with lower adjusted mean (95% confidence interval) 2-hour glucose (mg/dL) by -6.2 (-11.5 to -1.0; P=.02), 2-hour insulin (microunits/mL) by -15.1 (-26.8 to -3.5; P=.01), and natural log 2-hour insulin by -0.15 (-0.25 to -0.06; P<.01), and with higher insulin sensitivity index0,120 by 0.08 (0.02-0.15; P=.02), but no differences in plasma fasting glucose or insulin concentrations. CONCLUSION: Among postpartum women with recent gestational diabetes mellitus, breastfeeding an infant during the 2-hour 75-g OGTT may modestly lower plasma 2-hour glucose (5% lower on average) as well as insulin concentrations in response to ingestion of glucose.

Epidemiology of peripartum cardiomyopathy: incidence, predictors, and outcomes.

OBJECTIVES: To estimate the incidence, describe the mortality, and identify independent predictors of peripartum cardiomyopathy, a very serious cardiovascular complication of pregnancy associated with maternal morbidity and mortality among otherwise healthy women without prior heart disease. METHODS: We identified all cases of diagnosed heart failure that occurred among women within 1 month before to 5 months after delivery of a liveborn neonate in Kaiser Permanente Northern California delivery hospitals between 1995 and 2004. Incident peripartum cardiomyopathy was confirmed from medical records documenting dilated cardiomyopathy with reduced left ventricular systolic function after excluding women with prior heart failure or valvular disease. Data sources included medical records, electronic clinical databases, and state birth and death files. RESULTS: Among 227,224 eligible women, we confirmed 110 recognized peripartum cardiomyopathy cases (incidence: 4.84 per 10,000 live births, 95% confidence interval 3.98-5.83). Independent predictors included maternal age of 25 years or older, non-Hispanic African American and Filipino groups, parity of 4 or greater, multiple gestation, severe anemia, pre-existing and pregnancy-related hypertensive disorders, and hemolysis, elevated liver enzymes, low platelets syndrome. Maternal death rate (per 1,000 person-years) was higher among cases (6.12) than noncases (0.23; P<.001). Neonates whose mothers developed peripartum cardiomyopathy experienced poorer clinical outcomes. CONCLUSION: Within a large, diverse northern California population, 1 of every 2,066 women delivering a liveborn neonate had recognized, confirmed peripartum cardiomyopathy, which was associated with higher maternal and neonatal death rates and worse neonatal outcomes. Several readily available patient characteristics can be used to identify women at risk for this severe pregnancy complication. LEVEL OF EVIDENCE: II.

Duration of lactation and incidence of the metabolic syndrome in women of reproductive age according to gestational diabetes mellitus status: a 20-Year prospective study in CARDIA (Coronary Artery Risk Development in Young Adults).

OBJECTIVE: The objective of the study was to prospectively assess the association between lactation duration and incidence of the metabolic syndrome among women of reproductive age. RESEARCH DESIGN AND METHODS: Participants were 1,399 women (39% black, aged 18-30 years) in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, an ongoing multicenter, population-based, prospective observational cohort study conducted in the U.S. Women were nulliparous and free of the metabolic syndrome at baseline (1985-1986) and before subsequent pregnancies, and reexamined 7, 10, 15, and/or 20 years after baseline. Incident metabolic syndrome case participants were identified according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. Complementary log-log models estimated relative hazards of incident metabolic syndrome among time-dependent lactation duration categories by gestational diabetes mellitus (GDM) adjusted for age, race, study center, baseline covariates (BMI, metabolic syndrome components, education, smoking, physical activity), and time-dependent parity. RESULTS: Among 704 parous women (620 non-GDM, 84 GDM), there were 120 incident metabolic syndrome case participants in 9,993 person-years (overall incidence rate 12.0 per 1,000 person-years; 10.8 for non-GDM, 22.1 for GDM). Increased lactation duration was associated with lower crude metabolic syndrome incidence rates from 0-1 month through >9 months (P < 0.001). Fully adjusted relative hazards showed that risk reductions associated with longer lactation were stronger among GDM (relative hazard range 0.14-0.56; P = 0.03) than non-GDM groups (relative hazard range 0.44-0.61; P = 0.03). CONCLUSIONS: Longer duration of lactation was associated with lower incidence of the metabolic syndrome years after weaning among women with a history of GDM and without GDM, controlling for preconception measurements, BMI, and sociodemographic and lifestyle traits. Lactation may have persistent favorable effects on women's cardiometabolic health.

Childbearing may increase visceral adipose tissue independent of overall increase in body fat.

OBJECTIVE: To examine whether childbearing is associated with increased visceral adiposity and whether the increase is proportionally larger than other depots. METHODS AND PROCEDURES: This prospective study examined changes in adiposity assessed via computed tomography (CT) and dual-energy X-ray absorptiometry among 122 premenopausal women (50 black, 72 white) examined in 1995-1996 and again in 2000-2001. During the 5-year interval, 14 women had one interim birth and 108 had no interim births. Multiple linear regression models estimated mean (95% confidence interval (CI)) 5-year changes in anthropometric and adiposity measures by interim births adjusted for age, race, and changes in total and subcutaneous adiposity. RESULTS: We found no significant differences between one interim birth and no interim births for 5-year changes in weight, BMI, total body fat, subcutaneous adipose tissue, or total abdominal adipose tissue. Visceral adipose tissue increased by 40 and 14% above initial levels for 1 birth and 0 birth groups, respectively. Having 1 birth vs. 0 births was associated with a greater increase in visceral adipose tissue of 18.0 cm2 (4.8, 31.2), P<0.01; gain of 27.1 cm2 (14.5, 39.7) vs. 9.2 cm2 (4.8, 13.6), and a borderline greater increase in waist girth of 2.3 cm (0, 4.5), P=0.05; gain of 6.3 cm (4.1, 8.5) vs. 4.0 cm (3.2, 4.8), controlling for gain in total body fat and covariates. DISCUSSION: Pregnancy may be associated with preferential accumulation of adipose tissue in the visceral compartment for similar gains in total body fat. Further investigation is needed to confirm these findings and determine whether excess visceral fat deposition with pregnancy adversely affects metabolic risk profiles among women.

A 20-year prospective study of childbearing and incidence of diabetes in young women, controlling for glycemia before conception: the Coronary Artery Risk Development in Young Adults (CARDIA) Study.

OBJECTIVE: We sought to determine whether childbearing increases incidence of type 2 diabetes after accounting for preconception glycemia and gestational glucose intolerance. RESEARCH DESIGN AND METHODS: A prospective, biracial cohort was examined up to five times during 1985-2006 in the multicenter, U.S. population-based Coronary Artery Risk Development in Young Adults Study. The analysis included 2,408 women (1,226 black and 1,182 white) aged 18-30 years who were free of diabetes and had a fasting plasma glucose (FPG) <126 mg/dl at baseline. Incident diabetes was diagnosed by self-report, diabetes medication use, FPG >or=126 mg/dl, and/or plasma glucose >or=200 mg/dl after a 2-h oral glucose load. Time-dependent interim birth groups were those with zero and those with one or more births with or without gestational diabetes mellitus (GDM), stratified by baseline parity. Complementary log-log models estimated relative hazards of incident diabetes by interim births adjusted for age, race, family history of diabetes, and baseline covariates (FPG, BMI, education, smoking, and physical activity). RESULTS: Of 193 incident diabetes cases in 42,782 person-years (4.5 cases/1,000 person-years), 84 (44%) had one or more interim births. Among nulliparas at baseline, incident rates per 1,000 person-years were 3.2 (95% CI 2.4-4.1) for those with no births, 2.9 (1.8-3.9) for one or more births without GDM, and 18.4 (10.9-25.9) for one or more births with GDM; adjusted relative hazards (95% CI) were 0.9 (0.6-1.4) for one or more births without GDM and 3.8 (2.2-6.6) for one or more births with GDM versus no births. CONCLUSIONS: Childbearing did not elevate diabetes incidence among those with normal glucose tolerance during pregnancy (without GDM). GDM conferred the highest risk of developing diabetes independent of family history of diabetes and preconception glycemia and obesity.

Kinetics and molecular properties of pheromone binding and release.

Transient kinetic studies have shown that the uptake of the pheromone (bombykol) of the silkworm moth (Bombyx mori), by its pheromone-binding protein (PBP) BmorPBP, proceeds with an "on" rate of 0.068 +/- 0.01 microM(-1).s(-1). With the high concentration of PBP in the sensillar lymph (10 mM), the half-life for the uptake of pheromone in vivo is approximately equal to 1 ms. A pH-dependent conformational change (BmorPBP(B) --> BmorPBP(A)), associated with the release of pheromone, is a first-order reaction (k = 74.1 +/- 0.32 s(-1); t(1/2), 9.3 ms). Under physiological conditions, both reactions proceed with half-life times on the order of milliseconds, as is required for odorant-oriented navigation in insects. Molecular interactions of bombykol with both native and mutated PBPs were analyzed by a novel binding assay. A recombinant protein with the native conformation (BmorPBP) showed high binding affinity (K(D) = 105 nM) at pH 7 but low affinity (K(D) = 1,600 nM) at pH 5, when tested at both low and high KCl concentrations. A protein with a C-terminal segment deleted (BmorPBPDeltaP129-V142) was found to bind bombykol at pH 7 and at pH 5 with the same affinity as the native protein at pH 7, indicating that the C-terminal segment is essential for preventing binding at low pH. Binding studies with three mutated proteins (BmorPBPW37F, BmorPBPW127F, and BmorPBPW37A) showed that replacing Trp-37 (with Phe or Ala) or Trp-127 (with Phe) did not affect the binding affinity to bombykol. Fluorescence studies shed light on the contributions of Trp-37 and Trp-127 emissions to the overall fluorescence.

Protein that makes sense in the Argentine ant.

With a protein-based approach, we have identified and cloned the cDNA encoding a chemosensory protein (LhumCSP) in the Argentine ant, Linepithema humile. The open reading frame of the cloned cDNA encoded a signal peptide (20 residues), and a mature protein (pI 4.62) of 106 amino acid residues. The calculated molecular mass (12,453 Da) was in agreement with the molecular mass measured by on-line chromatography-electrospray ionization mass spectrometry (12,448 Da), given the formation of two disulfide bridges. LhumCSP shared sequence similarity with various CSPs, particularly those identified and/or cloned from moth species. Also, LhumCSP showed the hallmark of the chemosensory proteins, i.e., four well conserved cysteine residues. The antennal protein was not detected in non-olfactory tissues (leg and thorax) contrary to a putative pheromone-binding protein isolated from the thorax of the red imported fire ant, Solenopsis invicta. In addition, these findings suggest that, as in Orthopterans and Phasmids, the protein that makes sense in the Argentine ant is not an odorant-binding protein, but rather a chemosensory protein.

Odorant-binding proteins from a primitive termite.

Hitherto, odorant-binding proteins (OBPs) have been identified from insects belonging to more highly evolved insect orders (Lepidoptera, Coleoptera, Diptera, Hymenoptera, and Hemiptera), whereas only chemosensory proteins have been identified from more primitive species, such as orthopteran and phasmid species. Here, we report for the first time the isolation and cloning of odorant-binding proteins from a primitive termite species, the dampwood termite. Zootermopsis nevadensis nevadensis (Isoptera: Termopsidae). A major antennae-specific protein was detected by native PAGE along with four other minor proteins, which were also absent in the extract from control tissues (hindlegs). Multiple cDNA cloning led to the full characterization of the major antennae-specific protein (ZnevOBP1) and to the identification of two other antennae-specific cDNAs, encoding putative odorant-binding proteins (ZnevOBP2 and ZnevOBP3). N-terminal amino acid sequencing of the minor antennal bands and cDNA cloning showed that olfaction in Z. n. nevadensis may involve multiple odorant-binding proteins. Database searches suggest that the OBPs from this primitive termite are homologues of the pheromone-binding proteins from scarab beetles and antennal-binding proteins from moths.