Disulfide bond assignments of secreted Frizzled-related protein-1 provide insights about Frizzled homology and netrin modules.

Secreted Frizzled-related protein-1 (sFRP-1), a soluble protein that binds to Wnts and modulates Wnt signaling, contains an N-terminal domain homologous to the putative Wnt-binding site of Frizzled (Fz domain) and a C-terminal heparin-binding domain with weak homology to netrin. Both domains are cysteine-rich, having 10 and 6 cysteines in the Fz and heparin-binding domains, respectively. In this study, the disulfide linkages of recombinant sFRP-1 were determined. Numbering sFRP-1 cysteines sequentially from the N terminus, the five disulfide linkages in the Fz domain are 1-5, 2-4, 3-8, 6-10, and 7-9, consistent with the disulfide pattern determined for homologous domains of several other proteins. The disulfide linkages of the heparin-binding domain are 11-14, 12-15, and 13-16. This latter set of assignments provides experimental verification of one of the disulfide patterns proposed for netrin (NTR) modules and thereby supports the prediction that the C-terminal heparin-binding domain of sFRP-1 is an NTR-type domain. Interestingly, two subsets of sFRPs appear to have alternate disulfide linkage patterns compared with sFRP-1, one of which involves the loss of a disulfide due to deletion of a single cysteine from the NTR module, whereas the remaining cysteine may pair with a new cysteine introduced in the Fz domain of the protein. Analysis of glycosylation sites showed that sFRP-1 contains a relatively large carbohydrate moiety on Asn(172) (approximately 2.8 kDa), whereas Asn(262), the second potential N-linked glycosylation site, is not modified. No O-linked carbohydrate groups were detected. There was evidence of heterogeneous proteolytic processing at both the N and C termini of the recombinant protein. The predominant N terminus was Ser(31), although minor amounts of the protein with Asp(41) and Phe(50) as the N termini were observed. The major C-terminal processing event was removal of the terminal amino acid (Lys(313)) with only a trace amount of unprocessed protein detected.     

Airborne pollen calendar of Buca–Izmir, Turkey

This communication presents the level ofpollen in the atmosphere of Buca–Izmir, Turkey.The evaluation includes qualitative as well asquantitative results. Studies were carried outduring 1996–1997 using gravimetric method. Datawas recorded from lower (BUL. 1.60 m) andhigher (BHL. 20 m) levels. Aeropalynologicalresults revealed that the atmosphere in thisarea abounds in pollen from 55 taxa out ofwhich 24 are woody and 31 herbaceous. At bothlevels plant groups with higher pollendensities per square centimeter were trees(BHL. 89%, BUL. 73.7%), other herbs (BHL.6.6%, BUL. 20.4%), Gramineae (BHL. 3.8%,BUL. 4.9%) and unidentified taxa (BHL. 0.6%,BUL. 1%) respectively. However, at lowerlevel Pinus, Quercus, Oleaceae,Morus, Centaurea, Gramineae,Chenopodiceae/Amaranthaceae showed highestconcentration; whereasCupressaceae/Taxaceae, Quercus,Gramineae, Chenopodiaceae/Amaranthaceae andPlantago were dominant at higher level.The concentration of allergic taxaChenopodiaceae/Amaranthaceae, Cupressaceae/Taxaceae; Gramineae, Morus, Oleaceae, Pinus, Plantago and Quercus was highin the atmosphere of the study area. The pollencalendar of the area has been prepared inrelation to the atmospheric parameters.     

The Correlation Between Smoking Status of Family Members and Concentrations of Toxic Trace Elements in the Hair of Children

Hair analysis is a promising tool for routine clinical screening and diagnosis of heavy metal exposure and essential trace element status in the human body. Systemic intoxications have been identified by anomalously high values of toxins in hair samples. The aim of the present study is to evaluate the relationship between smoking habit of the family members and the levels of toxic and nontoxic trace elements in hair samples of children. The randomized cross-sectional controlled study comprised of 95 children (41 girls and 54 boys) between the ages of 1 and 6 years. After written informed consent was obtained, a face-to-face interview was conducted with the families about educational background, total income of the family, and smoking habits of family members. The mineral elements considered in this study were Zn, Se, B, V, Co, Mo, Mn, iron (Fe), Be, aluminum (Al), As, cadmium (Cd), lead (Pb), Hg, chromium (Cr), Ag, Be, nickel (Ni), copper (Cu), Sn, and antimony (Sb). Hair mineral contents were measured by inductively coupled plasma-mass spectrometry. The results showed that the levels of Cd, Pb, Cr, Sb, Fe, and Al in hair samples of children whose parents smoked were significantly higher than those whose parents were nonsmokers. The number of smokers and the frequency of smoking at home were positively correlated with Pb, Cd, Cu, Ni, and Sb levels found. At the same time, it was found that there was no correlation between toxic element concentrations and family income or educational background excluding the levels of Cd. A correlation was observed between the smoking status of family members and levels of toxic trace elements in hair where this correlation was more significant with the levels of Pb and Cd. High socioeconomic status and the level of education of family members did not have any effect on toxic trace levels in hair samples of children.     

Abscisic acid cross-talking with hydrogen peroxide and osmolyte compounds may regulate the leaf rolling mechanism under drought

Leaf rolling observed in some crops such as maize, rice, wheat and sorghum is an indicator of decreased water status. Moderate leaf rolling not tightly or early increases the photosynthesis and grain yield of crop cultivars under environmental stresses. Moreover, the effects of exogenous abscisic acid (ABA) on stomatal conductance, water status and synthesis of osmotic compounds are a well-known issue in plants subjected to water deficit. However, it is not clear how the cross-talk of ABA with H₂O₂ and osmolyte compounds affects the leaf rolling mechanism. Regulation mechanism of leaf rolling by ABA has been first studied in maize seedlings under drought stress induced by polyethylene glycol 6000 (PEG 6000) in this study. ABA treatment under drought stress reduced hydrogen peroxide (H₂O₂) content and the degree of leaf rolling (%) while the treatment-induced ABA synthesis, osmolyte levels (proline, polyamine and total soluble sugars) and some antioxidant enzyme activities in comparison to the plants that were not treated with ABA. Furthermore, exogenous ABA up-regulated the expression levels of arginine decarboxylase (ADC) and pyrroline-5-carboxylate synthase (P5CS) genes and down-regulated polyamine oxidase (PAO), diamine oxidase (DAO) and proline dehydrogenase (ProDH) gene expressions. When endogenous ABA content was decreased by the treatment of fluoridone (FLU) that is an ABA inhibitor, leaf rolling degree (%), H₂O₂ content and antioxidant enzyme activities increased, but osmolyte levels, ADC and P5CS gene expressions decreased. Finally, the treatment of ABA to maize seedlings exposed to drought stress resulted in the stimulation of the antioxidant system, osmotic adjustment and reduction of leaf rolling. We concluded that ABA can be a signal compound cross-talking H₂O₂, proline and polyamines and thus involved in the leaf rolling mechanism by providing osmotic adjustment. The results of this study can be used to provide data for the molecular breeding of maize hybrids with high grain yield by means of moderately rolled leaves.     

Genetic and epigenetic effects of salinity on in vitro growth of barley

Morphological, physiological and molecular changes were investigated in in vitro salt-stressed barley (Hordeum vulgare L. cv. Tokak). Mature embryos were cultured in Murashige and Skoog medium containing 0 (control), 50 and 100 mM NaCl for 20 days. Both concentrations inhibited shoot growth, decreased fresh weight and protein content, and increased SOD (EC 1.15.1.1) activity in a dose-dependent manner. The lower concentration increased root growth. Salinity caused nucleotide variations in roots, but did not affect shoot DNAs. The higher concentration caused methylation changes, mainly hypermethylation in shoots. This is the first study on genetic and epigenetic effects of salinity in barley.