Homodimerization of the Wnt Receptor DERAILED Recruits the Src Family Kinase SRC64B

Ryk pseudokinase receptors act as important transducers of Wnt signals, particularly in the nervous system. Little is known, however, of their interactions at the cell surface. Here, we show that a Drosophila Ryk family member, DERAILED (DRL), forms cell surface homodimers and can also heterodimerize with the two other fly Ryks, DERAILED-2 and DOUGHNUT ON 2. DERAILED homodimerization levels increase significantly in the presence of its ligand, WNT5. In addition, DERAILED displays ligand-independent dimerization mediated by a motif in its transmembrane domain. Increased dimerization of DRL upon WNT5 binding or upon the replacement of DERAILED''s extracellular domain with the immunoglobulin Fc domain results in an increased recruitment of the Src family kinase SRC64B, a previously identified downstream pathway effector. Formation of the SRC64B/DERAILED complex requires SRC64B''s SH2 domain and DERAILED''s PDZ-binding motif. Mutations in DERAILED''s inactive tyrosine kinase-homologous domain also disrupt the formation of DERAILED/SRC64B complexes, indicating that its conformation is likely important in facilitating its interaction with SRC64B. Finally, we show that DERAILED''s function during embryonic axon guidance requires its Wnt-binding domain, a putative juxtamembrane extracellular tetrabasic cleavage site, and the PDZ-binding domain, indicating that DERAILED''s activation involves a complex set of events including both dimerization and proteolytic processing.     

A Novel Biosurfactant Produced by Aureobasidium pullulans L3-GPY from a Tiger Lily Wild Flower,Lilium lancifolium Thunb.

Yeast biosurfactants are important biotechnological products in the food industry, and they have medical and cosmeceutical applications owing to their specific modes of action, low toxicity, and applicability. Thus, we have isolated and examined biosurfactant-producing yeast for various industrial and medical applications. A rapid and simple method was developed to screen biosurfactant-producing yeasts for high production of eco-friendly biosurfactants. Using this method, several potential niches of biosurfactant-producing yeasts, such as wild flowers, were investigated. We successfully selected a yeast strain, L3-GPY, with potent surfactant activity from a tiger lily, Lilium lancifolium Thunb. Here, we report the first identification of strain L3-GPY as the black yeast Aureobasidium pullulans. In addition, we isolated a new low-surface-tension chemical, designated glycerol-liamocin, from the culture supernatant of strain L3-GPY through consecutive chromatography steps, involving an ODS column, solvent partition, silica gel, Sephadex LH-20, and an ODS Sep-Pak cartridge column. The chemical structure of glycerol-liamocin, determined by mass spectrometry and nuclear magnetic resonance spectroscopy, indicates that it is a novel compound with the molecular formula C₃₃H₆₂O₁₂. Furthermore, glycerol-liamocin exhibited potent biosurfactant activity (31 mN/m). These results suggest that glycerol-liamocin is a potential novel biosurfactantfor use in various industrial applications.     

Seasonal Variation in Ischemic Stroke Incidence and Association with Climate: A Six‐Year Population‐Based Study

Questions about the seasonality of stroke remain controversial. Using a nationwide population‐based dataset, this study presents a time series analysis of seasonal patterns in ischemic stroke occurrence, along with their association with climate in Taiwan. Using data from the Taiwan National Health Insurance Research Database, a total of 168,977 visits to emergency departments between 1998 and 2003 for ischemic stroke were identified for patients ranging between 20 and 84 yrs of age. Monthly stroke incidences were calculated for 72 months, by sex and stroke subtype, and for the age groups 20–54, 55–64, 65–74, and ≥75 yrs per 100,000 of the population. We performed auto‐regressive integrated moving average (ARIMA) analysis to investigate the presence of seasonality and any association with climate for acute ischemic stroke events. We found no significant seasonal variation in the incidence of ischemic stroke for any age or sex groups. Furthermore, after adjusting for seasonality, month, and trend, the ARIMA regression model revealed only associations between ischemic stroke incidence and atmospheric pressure. We conclude that seasonality of ischemic stroke does not exist in Taiwan. Ischemic stroke incidence is, however, significantly related to atmospheric pressure.     

Evaluation of Repellency Effect of Two Natural Aroma Mosquito Repellent Compounds,Citronella and Citronellal*

Repellent efficacies of two natural aroma compounds, citronella and citronellal, against mosquitoes, Culex pipiens pallens, were evaluated both in field and in vitro. In vitro, the experiment was conducted with three controlled bands impregnated with 30% citronella extract, 15% citronella extract and 30% citronellal extract, and with bands impregnated 30% citronella in field. Data was obtained by the means of counting numbers bitten by mosquitoes per unit time, namely human bait method. Percentage repellencies of above three controlled bands were calculated at 86%, 73%, and 78%, respectively in vitro, and 80% in field, showing high repellent effectiveness against mosquitoes. This estimation was also confirmed by t‐test compared between control group and each experimental group.     

Site-specific racemization in aging alpha A-crystallin

Of all aspartyl residues in bovine alpha A-crystallin, only Asp-151 exhibits pronounced racemization. Asp-151 is also one of the sites where peptide bond cleavage occurs in in vivo aging alpha A-crystallin. This aspartyl residue is followed by an alanyl residue and resides in a flexible carboxyl terminal extension of alpha-crystallin. Both in vivo and in vitro racemization studies indicate that the pronounced and site-specific racemization of Asp-151 proceeds via formation of a succinimide intermediate. The in vivo racemization of aspartyl residues in alpha A-crystallin is discussed with regard to the proposed tertiary structure of alpha-crystallin.     

Feasibility of the immunohistochemical detection of endogenous steroids in paraffin-embedded ovarian tumours

Summary Formalin-fixed, paraffin-embedded samples from 25 ovarian granulosa cell tumours and six poorly differentiated ovarian carcinomas examined immunohistochemically for the presence of estradiol, testosterone and progesterone. Twenty-four of the 25 granulosa cell tumours stained for estradiol predominantly in granulosa cells and also in the theca cells, but none of the carcinomas were positive. All the granulosa cell tumours and five out of six carcinomas were positive for progesterone, while 13 granulosa cell tumours and three carcinomas stained moderately positive for testosterone.No clear-cut relationship was observed between positivity for estradiol in granulosa cell tumours and occurrence of endometrial hyperplasia. In two cases of granulosa cell tumours, 1–15% cells showed ultrastructural features of steroid synthesis: i.e. moderate to abundant smooth endoplasmic reticulum and mitochondria with tubular cristae. This is in contrast with the diffuse immunohistochemical staining reaction of granulosa cell tumours with antisteroid antibodies.To evalutate the significance of immunohistochemical for estradiol, four estradiol-containing tumours were tested by radioimmunoassay for the presence of estradiol before and after dehydration. As expected, treatment with organic solvent leads to a drastic reduction in estradiol content below the detection level of the assay. The result indicate that immunohistochemical staining for steroids of paraffin-embedded granulosa cell tumours if of limited value.     

Use of nonmotile mutants to identify a set of membrane proteins related to gliding motility in Cytophaga johnsonae.

Nonmotile mutants of the gliding bacterium Cytophaga johnsonae were examined to identify proteins that might be involved in gliding motility. Wild-type and mutant cell proteins were solubilized and fractionated by using Triton X-114, and the proteins that partitioned into the aqueous phase or the detergent phase were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for proteins that differed between wild-type and mutant cells. Seventeen proteins, ranging in size from 16 to 150 kilodaltons, were implicated by this technique as having some relationship to gliding and were designated Gld-1 through Gld-17. All Gld proteins behaved as integral membrane proteins, partitioning into the detergent phase. All 56 mutants examined exhibited changes in 1 or more of the Gld proteins, with the number of proteins altered in any mutant varying from 1 to 11. Several lines of evidence suggested that proteins Gld-12 through Gld-15 are glycoproteins. Analysis of banding patterns of detergent-fraction proteins of motile revertants supported the idea that the Gld proteins have a role in gliding motility.