Cephalometric study of facial growth in children after combined pushback and pharyngeal flap operations.

Linear and angular cephalometric measurements of children who had had combined palatal pushbacks and superiorly-based pharyngeal flaps do not show later growth retardation of the face. There was an inherent tendency for children with overt clefts of the secondary palate, classic submucous clefts, or occult submucous clefts to demonstrate pre-operatively a narrow SNA and SNB--but the difference between these angles (ANB) was normal.     

Effect of single-site charge-reversal mutations on the catalytic properties of yeast cytochrome c peroxidase: evidence for a single, catalytically active, cytochrome c binding domain

Forty-six charge-reversal mutants of yeast cytochrome c peroxidase (CcP) have been constructed in order to determine the effect of localized charge on the catalytic properties of the enzyme. The mutants include the conversion of all 20 glutamate residues and 24 of the 25 aspartate residues in CcP, one at a time, to lysine residues. In addition, two positive-to-negative charge-reversal mutants, R31E and K149D, are included in the study. The mutants have been characterized by absorption spectroscopy and hydrogen peroxide reactivity at pH 6.0 and 7.5 and by steady-state kinetic studies using recombinant yeast iso-1 ferrocytochrome c (C102T) as substrate at pH 7.5. Many of the charge-reversal mutations cause detectable changes in the absorption spectrum of the enzyme reflecting increased amounts of hexacoordinate heme compared to wild-type CcP. The increase in hexacoordinate heme in the mutant enzymes correlates with an increase in H 2O 2-inactive enzyme. The maximum velocity of the mutants decreases with increasing hexacoordination of the heme group. Steady-state velocity studies indicate that 5 of the 46 mutations (R31E, D34K, D37K, E118K, and E290K) cause large increases in the Michaelis constant indicating a reduced affinity for cytochrome c. Four of the mutations occur within the cytochrome c binding site identified in the crystal structure of the 1:1 complex of yeast cytochrome c and CcP [Pelletier, H., and Kraut, J. (1992) Science 258, 1748-1755] while the fifth mutation site lies outside, but near, the crystallographic site. These data support the hypothesis that the CcP has a single, catalytically active cytochrome c binding domain, that observed in the crystal structures of the cytochrome c/CcP complex.     

Bi-directional soil/atmosphere N2O exchange over two mown grassland systems with contrasting management practices

Nitrous oxide (N₂O) fluxes from soil under mown grassland were monitored using static chambers over three growing seasons in intensively and extensively managed systems in Central Switzerland. Emissions were largest following the application of mineral (NH₄NO₃) fertilizer, but there were also substantial emissions following cattle slurry application, after grass cuts and during the thawing of frozen soil. Continuous flux sampling, using automatic chambers, showed marked diurnal patterns in N₂O fluxes during emission peaks, with highest values in the afternoon. Net uptake fluxes of N₂O and subambient N₂O concentrations in soil open pore space were frequently measured on both fields. Flux integration over 2.5 years yields a cumulated emission of +4.7 kgN₂O‐N ha^?1 for the intensively managed field, equivalent to an average emission factor of 1.1%, and a small net sink activity of ?0.4 kg N₂O‐N ha^?1 for the unfertilized system. The data suggest the existence of a consumption mechanism for N₂O in dry, areated soil conditions, which cannot be explained by conventional anaerobic denitrification. The effect of fertilization on greenhouse gas budgets of grassland at the ecosystem level is discussed.     

The innate immune receptor MDA5 limits rotavirus infection but promotes cell death and pancreatic inflammation

Melanoma differentiation‐associated protein 5 (MDA5) mediates the innate immune response to viral infection. Polymorphisms in IFIH1, the gene coding for MDA5, correlate with the risk of developing type 1 diabetes (T1D). Here, we demonstrate that MDA5 is crucial for the immune response to enteric rotavirus infection, a proposed etiological agent for T1D. MDA5 variants encoded by minor IFIH1 alleles associated with lower T1D risk exhibit reduced activity against rotavirus infection. We find that MDA5 activity limits rotavirus infection not only through the induction of antiviral interferons and pro‐inflammatory cytokines, but also by promoting cell death. Importantly, this MDA5‐dependent antiviral response is specific to the pancreas of rotavirus‐infected mice, similar to the autoimmunity associated with T1D. These findings imply that MDA5‐induced cell death and inflammation in the pancreas facilitate progression to autoimmune destruction of pancreatic β‐cells.     

Nongenetic individuality in the host-phage interaction

Isogenic bacteria can exhibit a range of phenotypes, even in homogeneous environmental conditions. Such nongenetic individuality has been observed in a wide range of biological processes, including differentiation and stress response. A striking example is the heterogeneous response of bacteria to antibiotics, whereby a small fraction of drug-sensitive bacteria can persist under extensive antibiotic treatments. We have previously shown that persistent bacteria enter a phenotypic state, identified by slow growth or dormancy, which protects them from the lethal action of antibiotics. Here, we studied the effect of persistence on the interaction between Escherichia coli and phage lambda. We used long-term time-lapse microscopy to follow the expression of green fluorescent protein (GFP) under the phage lytic promoter, as well as cellular fate, in single infected bacteria. Intriguingly, we found that, whereas persistent bacteria are protected from prophage induction, they are not protected from lytic infection. Quantitative analysis of gene expression reveals that the expression of lytic genes is suppressed in persistent bacteria. However, when persistent bacteria switch to normal growth, the infecting phage resumes the process of gene expression, ultimately causing cell lysis. Using mathematical models for these two host–phage interactions, we found that the bacteria's nongenetic individuality can significantly affect the population dynamics, and might be relevant for understanding the coevolution of bacterial hosts and phages.     

Structural and functional coupling of Hsp90- and Sgt1-centred multi-protein complexes

Sgt1 is an adaptor protein implicated in a variety of processes, including formation of the kinetochore complex in yeast, and regulation of innate immunity systems in plants and animals. Sgt1 has been found to associate with SCF E3 ubiquitin ligases, the CBF3 kinetochore complex, plant R proteins and related animal Nod-like receptors, and with the Hsp90 molecular chaperone. We have determined the crystal structure of the core Hsp90–Sgt1 complex, revealing a distinct site of interaction on the Hsp90 N-terminal domain. Using the structure, we developed mutations in Sgt1 interfacial residues, which specifically abrogate interaction with Hsp90, and disrupt Sgt1-dependent functions in vivo, in plants and yeast. We show that Sgt1 bridges the Hsp90 molecular chaperone system to the substrate-specific arm of SCF ubiquitin ligase complexes, suggesting a role in SCF assembly and regulation, and providing multiple complementary routes for ubiquitination of Hsp90 client proteins.     

Growth Characteristics and Enzyme Activity in Batrachochytrium dendrobatidis Isolates

Eighty soil samples were collected from various sites of Bahrain and screened for presence of keratinophilic fungi using hair baiting techniques for isolation. Thirty-six isolates were recovered and identified. The cultures were identified using macro- and micromorphological features. Their identification was also confirmed by the BLAST search of sequences of ITS1-5.8S-ITS2 rDNA region against the NCBI/Gene bank data and compared with deposited sequences for confirmation. Eight species of five genera were isolated viz. Aphanoascus fulvuscence (8.75%), Aphanoascus punsolae (20.00%), Chrysosporium indicum (2.50%), Chrysosporium tropicum (2.50%), Chrysosporium zonatum (3.75%), Spiromastix warcupii (1.25%), Microsporum gypseum (3.75%), and Trichophyton mentagrophytes (2.50%). In conclusion, our study indicates that keratinophilic fungi do occur in the various soils of Bahrain. Moreover, the narrow diversity and low density of keratinophilic fungi in the investigated soils is expected and is emblematic to other hot arid environments.