Lack of a fusion requirement for development of bone marrow-derived epithelia

Analysis of developmental plasticity of bone marrow-derived cells (BMDCs) is complicated by the possibility of cell-cell fusion. Here we demonstrate that epithelial cells can develop from BMDCs without cell-cell fusion. We use the Cre/lox system together with beta-galactosidase and enhanced green fluorescent protein expression in transgenic mice to identify epithelial cells in the lung, liver, and skin that develop from BMDCs without cell fusion.     

The calicheamicin gene cluster and its iterative type I enediyne PKS

The enediynes exemplify nature's ingenuity. We have cloned and characterized the biosynthetic locus coding for perhaps the most notorious member of the nonchromoprotein enediyne family, calicheamicin. This gene cluster contains an unusual polyketide synthase (PKS) that is demonstrated to be essential for enediyne biosynthesis. Comparison of the calicheamicin locus with the locus encoding the chromoprotein enediyne C-1027 reveals that the enediyne PKS is highly conserved among these distinct enediyne families. Contrary to previous hypotheses, this suggests that the chromoprotein and nonchromoprotein enediynes are generated by similar biosynthetic pathways.     

Reduced MAP kinase phosphatase-1 degradation after p42/p44MAPK-dependent phosphorylation

The mitogen-activated protein (MAP) kinase cascade is inactivated at the level of MAP kinase by members of the MAP kinase phosphatase (MKP) family, including MKP-1. MKP-1 was a labile protein in CCL39 hamster fibroblasts; its degradation was attenuated by inhibitors of the ubiquitin-directed proteasome complex. MKP-1 was a target in vivo and in vitro for p42(MAPK) or p44(MAPK), which phosphorylates MKP-1 on two carboxyl-terminal serine residues, Serine 359 and Serine 364. This phosphorylation did not modify MKP-1's intrinsic ability to dephosphorylate p44(MAPK) but led to stabilization of the protein. These results illustrate the importance of regulated protein degradation in the control of mitogenic signaling.     

Dependence of Extensograph Parameters on Wheat Protein Composition Measured by SE-HPLC

Size-exclusion HPLC measurements were made on the total protein from flours of 158 wheat lines grown at five locations (31 at all sites and an extra one at three locations). Closely spaced cuts in the chromatograms were made at elution times differing by 0·4 min. The percentage of the protein that eluted up to each time was correlated with Extensograph dough maximum resistance (R_max) and dough extensibility (Ext). For R_max, maximal correlation (r=0·489*** for all locations) was obtained for the percentage of protein eluting before 13·2 min, corresponding to estimated molecular weights equal to and greater than 250 000. In the case of Ext, the highest correlation (0·859*** for all locations) was obtained for the percentage of protein in the flour which eluted before 16·8 min, which included essentially all the flour polymeric protein with estimated molecular weights above 52 000. The different dependencies of R_maxand Ext provide a basis for manipulating these parameters in predictable ways in breeding programs.     

Strain-specific vital rates in four Acartia tonsa cultures, I: Strain origin, genetic differentiation and egg survivorship

Successful development of planktonic copepods for use as live feed in marine aquaculture relies on optimization of environmental conditions for population growth and egg storage. This study examined strain-specific differences in egg survivorship during cold-storage-induced quiescence in four cultures of the widespread marine calanoid Acartia tonsa Dana, 1849. Experimental cultures were obtained from Øresund, Denmark (DIFRES), Kiel, Germany (KIEL), Turkey Point, Florida, USA (FL), and Mobile Bay, Alabama, USA (AL), and were shown to derive from three highly distinct mitochondrial clades. Eggs from Gulf of Mexico strains had low tolerance for cold storage, and showed very low hatching success after 10 days. In contrast, Baltic Sea strains produced eggs able to tolerate up to 150 days of cold storage, with the DIFRES strain showing the highest egg survivorship during the experiment. Eggs from the Kiel strain showed an increase in hatching over time, indicating the presence of dormant eggs. Parental rearing temperature was also found to affect egg survivorship during quiescence in the DIFRES strain, with lower hatching success observed among eggs produced at 25 °C than at 17 °C. The DIFRES strain is recommended as the optimal strain for use in aquaculture, and conditions for cold storage of eggs are discussed.     

Effects of dietary fatty acid composition on metabolic rate and responses to hypoxia in the European eel (Anguilla anguilla)

European eels (Anguilla anguilla, L.) were fed on a commercial diet supplemented either with 15% by dry feed weight of menhaden oil (MO), an oil rich in highly unsaturated fatty acids of the n-3 series (n-3 HUFA), or with 15% by dry feed weight of coconut oil (CO), an oil composed primarily of saturated fatty acids (SFA). Following 90 days of feeding, the mean final masses of eels fed the two different oil supplements were similar, and higher than the mean final mass of a group fed the commercial diet alone. The diets created two distinct phenotypes of eels, distinguished by the fatty acid (FA) composition of their tissue lipids. Eels fed MO had significantly more total n-3 FA and n-3 HUFA in muscle and liver lipids than did eels fed CO, leading to higher n-3/n-6 and eicosapentaenoic acid/arachidonic acid ratios in the MO group. Measurements of O₂ uptake (M_O2) revealed that the MO group had a significantly lower routine metabolic rate (RMR) than the CO group. When exposed to progressive hypoxia, both groups regulated M_O2 at routine normoxic levels until critical water O₂ partial pressures that were statistically similar (9.62±1.08 kPa in MO versus 7.57±1.07 kPa in CO), beyond which they showed a reduction in M_O2 below RMR. The MO group exhibited a significantly lower M_O2 than the CO group throughout hypoxic exposure, but the percentage reductions in M_O2 below their relative RMR were equal in both groups. During recovery to normoxia, both groups exhibited an increase in M_O2 to rates significantly higher than their RMR. Throughout recovery, M_O2 was significantly lower in the MO group compared with the CO group, but the percentage increases in M_O2 relative to RMR were equal in both. During progressive hypoxia, neither group exhibited a marked ventilatory reflex response, both showed similar reductions in blood O₂ partial pressure and content, and similar increases in plasma lactate. The results indicate that, although the n-3 HUFA-enriched MO group had a significantly lower routine metabolic rate than the CO group, the difference in aerobic metabolism did not influence the European eel's homeostatic regulation of M_O2 in hypoxia.     

Effect of Multiple Substitution of Glutenin and Gliadin Proteins on Flour Quality of Canada Prairie Spring Wheat

The effect of genetic substitution of two to four glutenin and gliadin subunits from a Canada Prairie Spring (CPS) cv. Biggar BSR into Alpha 16, another CPS wheat line, was studied for rheological and baking quality. Results from double substitution showed that the presence of a gliadin component from Biggar BSR (BGGL) and low molecular weight glutenin subunit 45 (LMW 45) contributed to improved dough strength characteristics. Presence of BGGL in combination with high molecular weight glutenin subunit 1 (HMW 1) or 17+18 (HMW 17+18) also showed improved dough strength over control Alpha lines. When three or four protein subunits were substituted, even though improved quality performance was observed, it was associated with the negative effect of lowered flour water absorptions in spite of similar protein contents. The study confirms that LMW glutenins, as well as gliadins, play an important role along with HMW glutenins in wheat flour quality. CPS wheat lines with improved dough strength properties can be selected from the double substitution lines with the combination of BGGL/LMW 45 and BGGL/HMW 1.