Henneguya michiganensis n. sp. (Cnidaria: Myxosporea) from the gills of muskellunge Esox masquinongy Mitchill(Esociformes: Esocidae)

Systematic Parasitology - Henneguya Thélohan, 1892 is the second most species rich genus of myxozoans, with reports from freshwater and marine fish worldwide. In the Great Lakes...     

The effect of fibrillar degradation on the mechanics of articular cartilage: a computational model

Biomechanics and Modeling in Mechanobiology - The pathogenesis and pathophysiological underpinnings of cartilage degradation are not well understood. Either mechanically or enzymatically mediated...     

The identification of a DNA polymorphism of the α fibrinogen gene,and the regional assignment of the human fibrinogen genes to 4q26-qter

Summary We have identified a common restriction fragment length polymorphism of the fibrinogen gene with the enzyme TaqI. This polymorphism is probably due to a single base change that creates or destroys a TaqI recognition site about 1000 basepairs from the 3 end of the fibrinogen géne. The frequency of the rare allele in 83 unrelated healthy individuals is 0.33. We have used in situ hybridisation of the fibrinogen cDNA to localise the gene on chromosome 4q29–31. We have confirmed this regional localisation by restriction fragment detection in a human x Chinese hamster somatic cell hybrid which contains a translocated human chromosome 4 with a breakpoint at 4q26. The , , and fibrinogen genes are all present on human chromosome 4q26-qter.     

Adhesion of an Amylolytic Arthrobacter sp. to Starch-Containing Plastic Films

Cells of the amylolytic bacterium KB-1 (thought to be an Arthrobacter sp.) adhered (~70%) to the surface of plastic films composed of starch-poly (methylacrylate) graft copolymer (starch-PMA), but did not adhere (<10%) to films composed of polymethylacrylate (PMA), polyethylene (PE), carboxymethyl cellulose, or a mixture of PE plus poly (ethylene-coacrylic acid) (EAA), starch plus PE, or starch plus PE and EAA. About 30% of the cells adhered to gelatinized insoluble starch. Dithiothreitol (5 mM), EDTA (5 mM), and soluble starch (1%, wt/vol) had little effect on the adhesion of KB-1 cells to starch-PMA films. However, glutaraldehyde-fixed cells, azide-treated cells, and heat-killed cells did not bind to starch-PMA plastic, suggesting that the observed adhesion required cell viability. Culture supernatant from 5-day-old KB-1 cultures contained a proteolytic enzyme that inhibited cell adhesion to starch-PMA plastics. Trypsin-treated KB-1 cells also lost their ability to bind to starch-PMA plastic. When washed free of trypsin and suspended in fresh medium, trypsin-treated bacteria were able to recover adhesion activity in the absence, but not in the presence, of the protein synthesis inhibitor chloramphenicol. These results suggested that adhesion of KB-1 to starch-PMA plastic may be mediated by a cell surface protein. Although KB-1 bacteria bound to starch-PMA plastic, they did not appear to degrade starch in these films. Evidence of starch degradation was observed for starch-PE-EAA plastics, where <10% of the bacteria was bound, suggesting that cell adhesion may not be a prerequisite for degradation of some starch-containing plastics.     

Identification of an intramitochondrially synthesized proteolipid associated with the mitochondrial ATPase complex as the product of a mitochondrial gene determining oligomycin resistance in Aspergillus nidulans.

The purification of an RNA-dependent DNA polymerase from the allantoic fluid of uninfected, embryonated chicken eggs is described in detail. Comparison to the polymerase of avian myeloblastosis virus shows that the two enzymes are different with respect to ion concentrations for optimal reaction, response to increasing concentrations of substrate, thermal stability and protection from thermal inactivation by viral RNA. It is concluded that the enzymes compared to each other are different proteins, which must have been coded by different genes. The RNA-dependent DNA polymerase in the allantoic fluid, therefore, does not derive from the partial or complete expression of the endogenous virus genome of the normal chicken cell or from infection by exogenous viruses.     

Bolus transit patterns in healthy subjects: a study using simultaneous impedance monitoring, videoesophagram, and esophageal manometry

Impedance monitoring (Imp) measures bolus transit. Combining Imp with manometry (EM) allows the effect of contractile patterns on transit to be assessed. The objective of this study is to identify bolus transit patterns in normal subjects, correlate Imp findings with the gold standard barium esophagram (Ba), and compare bolus transit with concomitant EM findings. Simultaneous Ba-Imp-EM was performed for 2 min in 15 normal volunteers (women, 11; age, 43 yr). Combined impedance-pressure sites were 5, 10, 15, 20 cm above the lower esophageal sphincter (LES). Boluses (10 ml) of 45% barium mixed with 0.9% NaCl were swallowed at > or = 20-s intervals (5-6 swallows/subject). Imp and Ba showed three bolus transit patterns, and the two methods were in agreement on the pattern type in 97% (83/86) of swallows. Normal bolus transit was found in 73% (61/83), and each had normal peristalsis and contraction amplitude. Stasis in the proximal esophagus occurred in 7 of 83 swallows despite normal manometric parameters in 4 of 7 swallows. Retrograde escape of a residue of incompletely cleared bolus from just above the LES to the site 5 cm above occurred in 14 of 83 swallows. Retrograde escape was triggered by the next swallow, occurred despite normal manometric parameters, and did not occur if the swallow interval was >30 s. In 55% (47/86) of swallows, air accumulated in the distal esophagus and persisted there for a mean of 3.6 s until cleared into the stomach. We conclude that impedance monitoring is a valid transit test and describe bolus transit patterns in normal subjects for comparison with patients with esophageal motility disorders.     

Chromium-resistant bacteria and cyanobacteria: impact on Cr(VI) reduction potential and plant growth

Two chromium-resistant bacterial strains, Bacillus cereus S-6 and Ochrobactrum intermedium CrT-1, and two cyanobacterial strains, Oscillatoria sp. and Synechocystis sp., were used in this study. At initial chromate concentrations of 300 and 600 microg K2CrO4 mL(-1), and an inoculum size of 9.6 x 10(7) cells mL(-1), B. cereus S-6 completely reduced Cr(VI), while O. intermedium CrT-1 reduced Cr(VI) by 98% and 70%, respectively after 96 h. At 100 microg K2CrO4 mL(-1), Synechocystis sp. MK(S) and Oscillatoria sp. BJ2 reduced 62.1% and 39.9% of Cr(VI), respectively, at 30 degrees C and pH 8. Application of hexavalent chromate salts adversely affected wheat seedling growth and anatomical characters. However, bacterial inoculation alleviated the toxic effects, as reflected by significant improvements in growth as well as anatomical parameters. Cyanobacterial strains also led to some enhancement of various growth parameters in wheat seedlings.     

Temporally controlled targeted somatic mutagenesis in skeletal muscles of the mouse

To generate temporally controlled targeted somatic mutations selectively and efficiently in skeletal muscles, we established a transgenic HSA-Cre-ER(T2) mouse line in which the expression of the tamoxifen-dependent Cre-ER(T2) recombinase is under the control of a large genomic DNA segment of the human skeletal muscle alpha-actin gene, contained in a P1-derived artificial chromosome. In this transgenic line Cre-ER(T2) is selectively expressed in skeletal muscles, and Cre-ER(T2)-mediated alteration of LoxP flanked (floxed) target genes is skeletal muscle-specific and strictly tamoxifen-dependent. HSA-Cre-ER(T2) mice should be of great value to analyze gene function in skeletal muscles, and to establish animal models of human skeletal muscle disorders.     

RNAi-induced targeted silencing of developmental control genes during chicken embryogenesis

The RNA interference technique is a powerful tool to understand gene function. Intriguingly, RNA interference cannot only be used for cells in vitro, but also in living organisms. Here, we have adapted the method for use in the chick embryo. However, this technique is limited by the uncertainty in predicting the RNAi transfection efficiency and site in the embryo. Hence, we elaborated a modified vector system, pEGFP-shRNA, which can coexpress enhanced green fluorescent protein (EGFP) and short hairpin RNA (shRNA) simultaneously to facilitate analysis of gene silencing in chicken embryos. We tested the silencing of two highly conserved genes (cAxin2, cParaxis), which play crucial roles in chicken embryonic developmental processes. For each target gene, four to five small DNA inserts, each of them encoding one shRNA, were selected and cloned individually to the vector downstream of the Pol III promoter (either human H1 or U6 promoter), which shared with highly conserved motifs in human and chicken. The pEGFP-shRNA constructs were electroporated into the neural tube or somites. After subsequent re-incubation of 24 h, the EGFP expression, with green fluorescent signal, indicated the transfected regions in the neural tube or somites. The EGFP expressing embryos were further submitted into the process of in situ hybridization for examination of the silencing effects. The results show that the EGFP signal in transfected areas correlated with the silencing of the target genes (cAxin2, cParaxis). The cAxin2 expression was inhibited by shRNAs of either targeting the RGS domain or the DAX domain coding region. The cParaxis mRNA level in transgenic somites and the related migratory myogenic population was also reduced. The results suggest that our novel dual expression EGFP-shRNA system opens a new possibility to study gene function in a convenient and efficient way.