Carbon-13 nuclear magnetic resonance of heme carbonyls. Cytochrome c and carboxymethyl derivatives of cytochrome c.

Carbonyl complexes of horse cytochrome c and various carboxymethylated derivatives have been examined using 13C NMR (carbon-13 nuclear magnetic resonance) spectroscopy. The multiplicity and chemical shift of the 13CO resonance were found to be functions of pH and the extent of alkylation. Correlations have been made among prominent features of the chemical shift titration curves and changes in the environment of the heme. A simple model compatible with the bulk of previous observations has been suggested to account for the several carbonyl resonance peaks and the complex behavior of the chemical shift with changes in pH.     

Autocatalytic activation of the proenzyme form of the C1s subunit of the first component of complement.

The autocatalytic activation of the proenzyme form of the Cls subunit of the first component of complement is reported for the first time. Incubation of the purified proenzyme at 37° and pH 7.4 results in the evolution of esterolytic activity according to a second-order autocatalytic rate law. The lag phase portion of the sigmoidal activation curve can be shortened either by increasing the proenzyme concentration or by addition of the activated Cls subunit.     

Inuit myopia: an environmentally induced "epidemic"?

Among Inuit less than 30 years old the prevalence of myopia is far in excess of that of their elders. This is especially true for females. There seems to be little, if any, genetic contribution to this "epidemic" of myopia in the young. The age and sex distribution indicates the likelihood of an environmental factor, probably cultural, being responsible for the current pattern. Other data implicate school attendance as a possible etiologic factor.     

Detection of the intracellular ras p21 oncogene product by flow cytometry

Rapid identification of the expression of oncogene products in specific cell types could potentially be useful in the diagnosis and treatment of human malignancy. We have now observed that through the use of lysolecithin permeabilization and fluorescence-activated flow cytometry, cells expressing high levels of the v-Ha-ras oncogene product, p21, can readily be distinguished from the nontransformed parent cells in a rapid and quantitative manner.     

Sleep-disordered breathing, pharyngeal size and soft tissue anatomy in children.

We tested the hypothesis that pharyngeal geometry and soft tissue dimensions correlate with the severity of sleep-disordered breathing. Magnetic resonance images of the pharynx were obtained in 18 awake children, 7-12 yr of age, with obstructive apnea-hypopnea index (OAHI) values ranging from 1.81 to 24.2 events/h. Subjects were divided into low-OAHI (n = 9) and high-OAHI (n = 9) groups [2.8 +/- 0.7 and 13.5 +/- 4.9 (SD) P < 0.001]. The OAHI correlated positively with the size of the tonsils (r2 = 0.42, P = 0.024) and soft palate (r2 = 0.33, P = 0.049) and inversely with the volume of the oropharyx (r2 = 0.42, P = 0.038). The narrowest point in the pharyngeal airway was smaller in the high-compared with the low-OAHI group (4.4 +/- 1.2 vs. 6.0 +/- 1.3 mm; P = 0.024), and this point was in the retropalatal airway in all but two subjects. The airway cross-sectional area (CSA)-airway length relation showed that the high-OAHI group had a narrower retropapatal airway than the low-OAHI group, particularly in the retropalatal region where the soft palate, adenoids, and tonsils overlap (P = 0.001). The "retropalatal air space," which we defined as the ratio of the retropalatal airway CSA to the CSA of the soft palate, correlated inversely with the OAHI (r2 = 0.49, P = 0.001). We conclude that 7- to 12-yr-old children with a narrow retropalatal air space have significantly more apneas and hypopneas during sleep compared with children with relatively unobstructed retropalatal airways.     

Understanding the role of wild ruminants in anthelmintic resistance in livestock

Wild ruminants are susceptible to infection from generalist helminth species, which can also infect domestic ruminants. A better understanding is required of the conditions under which wild ruminants can act as a source of helminths (including anthelmintic-resistant genotypes) for domestic ruminants, and vice versa, with the added possibility that wildlife could act as refugia for drug-susceptible genotypes and hence buffer the spread and development of resistance. Helminth infections cause significant productivity losses in domestic ruminants and a growing resistance to all classes of anthelmintic drug escalates concerns around helminth infection in the livestock industry. Previous research demonstrates that drug-resistant strains of the pathogenic nematode Haemonchus contortus can be transmitted between wild and domestic ruminants, and that gastro-intestinal nematode infections are more intense in wild ruminants within areas of high livestock density. In this article, the factors likely to influence the role of wild ruminants in helminth infections and anthelmintic resistance in livestock are considered, including host population movement across heterogeneous landscapes, and the effects of climate and environment on parasite dynamics. Methods of predicting and validating suspected drivers of helminth transmission in this context are considered based on advances in predictive modelling and molecular tools.     

The growth of soybean under free air [CO<Subscript>2</Subscript>] enrichment (FACE) stimulates photosynthesis while decreasing in vivo Rubisco capacity

Down-regulation of light-saturated photosynthesis (A_sat) at elevated atmospheric CO₂ concentration, [CO₂], has been demonstrated for many C₃ species and is often associated with inability to utilize additional photosynthate and/or nitrogen limitation. In soybean, a nitrogen-fixing species, both limitations are less likely than in crops lacking an N-fixing symbiont. Prior studies have used controlled environment or field enclosures where the artificial environment can modify responses to [CO₂]. A soybean free air [CO₂] enrichment (FACE) facility has provided the first opportunity to analyze the effects of elevated [CO₂] on photosynthesis under fully open-air conditions. Potential ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation (V_c,max) and electron transport through photosystem II (J_max) were determined from the responses of A_sat to intercellular [CO₂] (C_i) throughout two growing seasons. Mesophyll conductance to CO₂ (g_m) was determined from the responses of A_sat and whole chain electron transport (J) to light. Elevated [CO₂] increased A_sat by 15–20% even though there was a small, statistically significant, decrease in V_c,max. This differs from previous studies in that V_c,max/J_max decreased, inferring a shift in resource investment away from Rubisco. This raised the C_i at which the transition from Rubisco-limited to ribulose-1,5-bisphosphate regeneration-limited photosynthesis occurred. The decrease in V_c,max was not the result of a change in g_m, which was unchanged by elevated [CO₂]. This first analysis of limitations to soybean photosynthesis under fully open-air conditions reveals important differences to prior studies that have used enclosures to elevate [CO₂], most significantly a smaller response of A_sat and an apparent shift in resources away from Rubisco relative to capacity for electron transport.Abbreviations FACE Free air [CO₂] enrichment - Rubisco Ribulose-1,5-bisphosphate carboxylase/oxygenase - RuBP Ribulose-1,5-bisphosphate - SoyFACE Soybean free air [CO₂] enrichment - VPD Vapor pressure deficit     

ARID3B Directly Regulates Ovarian Cancer Promoting Genes

The DNA-binding protein AT-Rich Interactive Domain 3B (ARID3B) is elevated in ovarian cancer and increases tumor growth in a xenograft model of ovarian cancer. However, relatively little is known about ARID3B''s function. In this study we perform the first genome wide screen for ARID3B direct target genes and ARID3B regulated pathways. We identified and confirmed numerous ARID3B target genes by chromatin immunoprecipitation (ChIP) followed by microarray and quantitative RT-PCR. Using motif-finding algorithms, we characterized a binding site for ARID3B, which is similar to the previously known site for the ARID3B paralogue ARID3A. Functionality of this predicted site was demonstrated by ChIP analysis. We next demonstrated that ARID3B induces expression of its targets in ovarian cancer cell lines. We validated that ARID3B binds to an epidermal growth factor receptor (EGFR) enhancer and increases mRNA expression. ARID3B also binds to the promoter of Wnt5A and its receptor FZD5. FZD5 is highly expressed in ovarian cancer cell lines, and is upregulated by exogenous ARID3B. Both ARID3B and FZD5 expression increase adhesion to extracellular matrix (ECM) components including collagen IV, fibronectin and vitronectin. ARID3B-increased adhesion to collagens II and IV require FZD5. This study directly demonstrates that ARID3B binds target genes in a sequence-specific manner, resulting in increased gene expression. Furthermore, our data indicate that ARID3B regulation of direct target genes in the Wnt pathway promotes adhesion of ovarian cancer cells.