Do rumen Bacteroidetes utilize an alternative mechanism for cellulose degradation?

Uncultured and therefore uncharacterized Bacteroidetes lineages are ubiquitous in many natural ecosystems which specialize in lignocellulose degradation. However, their metabolic contribution remains mysterious, as well-studied cultured Bacteroidetes have been shown to degrade only soluble polysaccharides within the human distal gut and herbivore rumen. We have interrogated a reconstructed genome from an uncultured Bacteroidetes phylotype that dominates a switchgrass-associated community within the cow rumen. Importantly, this characterization effort has revealed the first preliminary evidence for polysaccharide utilization locus (PUL)-catalyzed conversion of cellulose. Based on these findings, we propose a further expansion of the PUL paradigm and the saccharolytic capacity of rumen Bacteroidetes species to include cellulose, the most abundant terrestrial polysaccharide on Earth. Moreover, the perspective of a cellulolytic PUL lays the foundation for PULs to be considered an alternative mechanism for cellulose degradation, next to cellulosomes and free-enzyme systems.

Interactions of PIN and PGP auxin transport mechanisms.

Polarized transport of the plant hormone auxin influences multiple growth processes in plants and is regulated by plasma-membrane-localized efflux and uptake carriers. The PGP (P-glycoprotein) ABC transporters (ATP-binding-cassette transporters), PIN (pin-formed) subfamily of major facilitator proteins and members of AUX/LAX families have been shown to independently transport auxin both in planta and in heterologous systems. However, PIN- and PGP-mediated transport in heterologous systems exhibits decreased substrate specificity and inhibitor-sensitivity compared with what is seen in plants and plant cells. To determine whether PIN-PGP interactions enhance transport specificity, we analysed interactions of the representative auxin-transporting PGPs with PIN1 and AUX1 in planta and in heterologous systems. Here, we provide evidence that PINs and PGPs interact and function both independently and co-ordinately to control polar auxin transport and impart transport specificity and directionality. These interactions take place in protein complexes stabilized by PGPs in detergent-resistant microdomains.

Consideration of acoustic reflex magnitude (ARM) in cases of idiopathic facial paralysis.

Contralaterally elicited acoustic reflex growth functions were obtained from both ears of patients with unilateral idiopathic facial paralysis. Comparison was then made between the normal and impaired reflex arc by means of a simple calculation procedure. The resultant acoustic reflex magnitude (ARM) score was used to evaluate the symmetry of these responses, thereby providing an objective quantification of the functional status of the impaired reflex arc. These measures were found to be highly correlated with both the degree and rate of recovery of the facial motor impairment.

Experimental otitis media with effusion: an immune-complex-mediated response.

The possibility that immune complexes cause otitis media with effusion (OME) has been previously proposed. In order to test this hypothesis we developed an animal model in which immune complexes were injected into the middle ears of chinchillas and the animals killed at various time intervals thereafter. Moderate inflammatory changes were seen in animals killed four hours postinjection, whereas intense inflammation was observed in those killed at 24 hours. Inflammatory changes observed included capillary dilatation with increased capillary permeability, migration of polymorphonuclear leukocytes into the sub-mucosa, hemorrhage, and damage to and actual disruption of the subepithelial basement membrane. These changes are consistent with a complement-mediated acute inflammatory reaction. Although no definite conclusion can be made concerning the etiologic role of immune complex in OME, our findings show that immune complexes can cause acute inflammatory changes in the middle ear of the experimental animal.

Myringostomy for middle ear effusions. Results of a two-year study.

From 1972 to 1974, 736 children had tympanostomy tubes inserted for chronic serous otitis media resistant to medical therapy. The total number of ears involved was 2,237. The cleft palate patients constituted 8.8% of the total and had 15.4% of all procedures. Patients with allergy comprised 19% of the total population and had a higher incidence of otitis media following tube insertion. Adenoidectomy was performed in 44% of all patients and 35% of these required further tube insertions, suggesting that adenoidectomy in combination with tube insertion is not necessarily the primary treatment of choice. Children under six made up 78.5% of the total. The most common complication, a draining ear with an incidence of 15.1% was treated successfully with aqueous Merthiolate irrigations. There were 14 tympanic membrane perforations.