Conservation of cysteine residues in fungal histidine acid phytases

Amino acid sequence analysis of fungal histidine acid phosphatases displaying phytase activity has revealed a conserved eight-cysteine motif. These conserved amino acids are not directly associated with catalytic function; rather they appear to be essential in the formation of disulfide bridges. Their role is seen as being similar to another eight-cysteine motif recently reported in the amino acid sequence of nearly 500 plant polypeptides. An additional disulfide bridge formed by two cysteines at the N-terminus of all the filamentous ascomycete phytases was also observed. Disulfide bridges are known to increase both stability and heat tolerance in proteins. It is therefore plausible that this extra disulfide bridge contributes to the higher stability found in phytase from some Aspergillus species. To engineer an enhanced phytase for the feed industry, it is imperative that the role of disulfide bridges be taken into cognizance and possibly be increased in number to further elevate stability in this enzyme.     

Isolated congenital anonychia cases with coincident chromosomal fragility

Isolated anonychia without any associated phenotypical disturbances is one of the rarest anomalies of congenital nail disorders. Some or all fingers of the hands or feet could be affected. Anonychia can be encountered in dermatologic disorders like pemphigus, lichen planus, epidermolysis bullosa; it can also be seen as a component of some syndromes like Nail-Patella and Cooks syndromes. We present a sister couple in whom all fingernails and toenails were lacking without any additional physical sign. A fragile chromosomal site was also encountered in peripheral chromosome analysis in the long arm of the chromosome 10 in both of the cases.     

Differential induction of apoptosis by cigarette smoke extract in primary human lung fibroblast strains: implications for emphysema

Cigarette smoke is the principal cause of emphysema. Recent attention has focused on the loss of alveolar fibroblasts in the development of emphysema. Fibroblasts may become damaged by oxidative stress and undergo apoptosis as a result of cigarette smoke exposure. Not all smokers develop lung diseases associated with tobacco smoke, a fact that may reflect individual variation among human fibroblast strains. We hypothesize that fibroblasts from different human beings vary in their ability to undergo apoptosis after cigarette smoke exposure. This could account for emphysematous changes that occur in the lungs of some but not all smokers. Primary human lung fibroblast strains were exposed to cigarette smoke extract (CSE) and assessed for viability, morphological changes, and mitochondrial transmembrane potential as indicators of apoptosis. We also examined the generation of intracellular reactive oxygen species (ROS), 4-hydroxy-2-nonenal, and changes in glutathione (GSH) and glutathione disulfide (GSSG) levels. Each human lung fibroblast strain exhibited a differential sensitivity to CSE as judged by changes in mitochondrial membrane potential, viability, ROS generation, and glutathione production. Interestingly, the thiol antioxidants N-acetyl-L-cysteine and GSH eliminated CSE-induced changes in fibroblast morphology such as membrane blebbing, nuclear condensation, and cell size and prevented alterations in mitochondrial membrane potential and the generation of ROS. These findings support the concept that oxidative stress and apoptosis are responsible for fibroblast death associated with exposure to tobacco smoke. Variations in the sensitivity of fibroblasts to cigarette smoke may account for the fact that only some smokers develop emphysema.     

An unusual class of PITX2 mutations in Axenfeld-Rieger syndrome

BACKGROUND: Mutations in the PITX2 homeobox gene are known to contribute to Axenfeld-Rieger syndrome (ARS), an autosomal-dominant developmental disorder. Although most mutations are in the homeodomain and result in a loss of function, there is a growing subset in the C-terminal domain that has not yet been characterized. These mutations are of particular interest because the C-terminus has both inhibitory and stimulatory activities. METHODS: In this study we used a combination of in vitro DNA binding and transfection reporter assays to investigate the fundamental issue of whether C-terminal mutations result in gain or loss of function at a cellular level. RESULTS: We report a new frameshift mutation in the PITX2 allele that predicts a truncated protein lacking most of the C-terminal domain (D122FS). This newly reported mutant and another ARS C-terminal mutant (W133Stop) both have greater binding than wild-type to the bicoid element. Of interest, the mutants yielded approximately 5-fold greater activation of the prolactin promoter in CHO cells, even though the truncated proteins were expressed at lower levels than the wild-type protein. The truncated proteins also had greater than wild-type activity in 2 other cell lines, including the LS8 oral epithelial line that expresses the endogenous Pitx2 gene. CONCLUSIONS: The results indicate that the PITX2 C-terminal domain has inhibitory activity and support the notion that ARS may also be caused by gain-of-function mutations.     

Antimicrobial activity of catechol and pyrogallol as allelochemicals

Catechol and pyrogallol are allelochemicals which belong to phenolic compounds synthesized in plants. Their antimicrobial activities were investigated on three bacteria (Pseudomonas putida, Pseudomonas pyocyanea, Corynebacterium xerosis) and two fungi (Fusarium oxysporum, Penicillium italicum) phytopathogenic species as test organisms using the disc diffusion method. Both catechol and pyrogallol were found to have antibacterial effects on all the bacteria used in the study at 5 and 10 mM concentrations. Catechol has also been found to have an antifungal effect on the fungi used in the study, whereas no antifungal effects of pyrogallol were observed. The most sensitive species among the bacteria was P. putida which was inhibited by the allelochemicals even at 1 mM concentration.     

Map position of phosphoglucomutase (Pgm) locus on autosome IV of house fly (Diptera: Muscidae)

We determined the map position of phosphoglucomutase (Pgm) locus on autosome IV of housefly, Musca domestica L. (Diptera: Muscidae), by using three and five point linkage test crosses. Test strains had visible mutant markers (car, bwb, cyw, and aabys). We analyzed 1738 offspring in total from two groups of single-pair matings by electrophoresis. Here, we report the linkage of Pgm locus to autosome IV loci curly wing (cyw) and yellow eyes (ye) with recombination frequency of 16.9 and 1.1%, respectively. We combined the distances calculated from this study and the previously published data. An updated linkage map of the M. domestica L. Autosome IV was drawn based on combined data in terms of real map units obtained from the mapping function.     

Denitrification and nitrous oxide emissions from riparian forests soils exposed to prolonged nitrogen runoff

Compared to upland forests, riparian forest soils have greater potential to remove nitrate (NO₃) from agricultural runoff through denitrification. It is unclear, however, whether prolonged exposure of riparian soils to nitrogen (N) loading will affect the rate of denitrification and its end products. This research assesses the rate of denitrification and nitrous oxide (N₂O) emissions from riparian forest soils exposed to prolonged nutrient runoff from plant nurseries and compares these to similar forest soils not exposed to nutrient runoff. Nursery runoff also contains high levels of phosphate (PO₄). Since there are conflicting reports on the impact of PO₄ on the activity of denitrifying microbes, the impact of PO₄ on such activity was also investigated. Bulk and intact soil cores were collected from N-exposed and non-exposed forests to determine denitrification and N₂O emission rates, whereas denitrification potential was determined using soil slurries. Compared to the non-amended treatment, denitrification rate increased 2.7- and 3.4-fold when soil cores collected from both N-exposed and non-exposed sites were amended with 30 and 60 μg NO₃-N g⁻¹ soil, respectively. Net N₂O emissions were 1.5 and 1.7 times higher from the N-exposed sites compared to the non-exposed sites at 30 and 60 μg NO₃-N g⁻¹ soil amendment rates, respectively. Similarly, denitrification potential increased 17 times in response to addition of 15 μg NO₃-N g⁻¹ in soil slurries. The addition of PO₄ (5 μg PO₄-P g⁻¹) to soil slurries and intact cores did not affect denitrification rates. These observations suggest that prolonged N loading did not affect the denitrification potential of the riparian forest soils; however, it did result in higher N₂O emissions compared to emission rates from non-exposed forest soils.     

Temperature-dependent development and reproductive traits of <Emphasis Type="Italic">Tetranychus macfarlanei</Emphasis> (Acari: Tetranychidae)

Development and reproductive traits of Tetranychus macfarlanei Baker & Pritchard (Acari: Tetranychidae) were investigated on kidney bean, Phaseolus vulgaris L., at eleven constant temperatures. Tetranychus macfarlanei was able to develop and complete its life cycle at temperatures ranging from 17.5 to 37.5°C. At 15 and 40°C, a few eggs (2–4%) hatched but further development was arrested. Development from egg to adult was slowest at 17.5°C and fastest at 35°C for both females and males. Using Ikemoto and Takai’s linear model, the estimated lower developmental thresholds for egg-to-female adult, egg-to-male adult and egg-to-egg development were 12.9–13.0°C. The thermal constants for the respective stages were 110.85, 115.99 and 125.32 degree-days (DD). The intrinsic optimum temperatures (T _Φ) calculated by non-linear SSI model were determined as 24.4, 24.4 and 24.2°C for egg-to-female adult, egg-to-male adult and egg-to-egg development, respectively. The net reproductive rate (R ₀) was highest at 25°C (167.4 females per female) and lowest at 17.5°C (42.6 females per female). The intrinsic rate of natural increase, r _m, increased linearly with the rising of temperature from 0.102 at 17.5°C to 0.441 day⁻¹ at 35°C. These values suggested that T. macfarlanei could be growing quickly in response to increasing temperatures from 17.5 to 35°C and provide a basis for predicting its potential geographical range.