Seasonal and storm event nutrient removal by a created wetland in an agricultural watershed

This study examines the effectiveness of a 1.2-ha created/restored emergent marsh at reducing nutrients from a 17.0 ha agricultural and forested watershed in the Ohio River Basin in west central Ohio, USA, during base flow and storm flow conditions. The primary source of water to the wetland was surface inflow, estimated in water year 2000 (October 1999–September 2000) to be 646 cm/year. The wetland also received a significant amount of groundwater discharge at multiple locations within the site that was almost the same in quantity as the surface flow. The surface inflow had 2-year averages concentrations of 0.79, 0.033, and 0.16 mg L⁻¹ for nitrate + nitrite (as N), soluble reactive phosphorus (SRP), and total phosphorus (TP), respectively. Concentrations of nitrate–nitrite, SRP, and TP were 40, 56, and 59% lower, respectively, at the outflow than at the inflow to the wetland over the 2 years of the study. Concentrations of SRP and TP exported from the wetland increased significantly (α = 0.05) during precipitation events in 2000 compared to dry weather flows, but concentrations of nitrate–nitrite did not increase significantly. During these precipitation events the wetland retained 41% of the nitrate–nitrite, 74% of the SRP, and 28% of the TP (by mass). The wetland received an average of 50 g N m⁻² per year of nitrate–nitrite and 7.1 g m⁻² per year of TP in 2000. Retention rates for the wetland were 39 g N m⁻² per year of nitrates and 6.2 g P m⁻² per year. These are close to rates suggested in the literature for sustainable non-point source retention by wetlands. The design of this wetland appears to be suitable as it retained a significant portion of the influent nutrient load and did not lose much of its retention capacity during heavy precipitation events. Some suggestions are given for further design improvements.     

Utilization of milk energy by suckling mink kits

A total of 36 mink dams and their litters of 3, 6 or 9 kits were used for determination of milk intake of the suckling young by means of deuterium dilution technique, and chemical composition of milk and of kit bodies. Measurements were performed during lactation weeks 1?–?4, each week with 3 dams with each litter size. Milk intake was determined over a 48?h measurement period, and by the end of this milk samples were collected and 2 kits (litters of 6 and 9) or 1 kit per litter (litters of 3) were killed for body chemical composition. Based on the results, different models were applied for calculation of the energetic efficiency of milk. Dam milk yield increased steadily from week 1 until week 3 but only slightly from week 3 to 4. The increase declined with increasing litter size, and for dams suckling 9 kits the increment from week 3 to week 4 was only 2?g. The dry matter content of milk increased significantly as lactation progressed, being reflected in crude protein increasing from 6.9% in lactation week 1 to 8.1% in week 4. Milk fat increased concomitantly from 5.6% to 8.0%. In kit bodies, crude protein content increased from 9.4% in week 1 to about 12% in weeks 3 and 4. Body fat content increased from week 1 (4.1%) to week 3 (8.4%) and then declined in week 4 (7.1%). Animals suckled in litters of 3 kits had the highest milk intake and live weight and kits suckled in litters of 9 had the lowest milk intake, live weight and daily gain. In terms of milk intake per g gain kits in litters of 6 were the most efficient, with 4.1?g milk per g body gain. The metabolizable energy requirement for maintenance (MEm) was estimated to 448 kJ/kg^0.75 and the efficiency of utilization of ME for body gain (k_g) to 0.67, the estimates being higher (MEm) or in good agreement with previous findings (k_g) in suckling mink kits.     

Non-redox-active small-molecules can accelerate oxidative protein folding by novel mechanisms

Multi-disulfide-bond-containing proteins acquire their native structures through an oxidative folding reaction which involves formation of native disulfide bonds through thiol-disulfide exchange reactions between cysteines and disulfides coupled to a conformational folding event. Oxidative folding rates of the four-disulfide-bond-containing protein bovine pancreatic ribonuclease A (RNase A) in the presence of the synthetic redox-active molecule, (+/-)-trans-1,2-bis(2-mercaptoacetamido)cyclohexane (BMC), and in combination with non-redox-active trimethylamine-N-oxide (TMAO), and trifluorethanol were determined by HPLC analysis. The data indicate that regeneration of RNase A is enhanced 2-fold by BMC (50 microM) and 3-fold upon addition of TMAO (0.2 M) and TFE (3% v/v) relative to control experiments performed in the absence of small-molecules. Examination of the native tendency of the fully-reduced polypeptide and the stability of key folding intermediates suggests that the increased oxidative folding rate can be attributed to native-like elements induced within the fully-reduced polypeptide and the stabilization of native-like species by added non-redox-active molecules.     

Rtt107/Esc4 binds silent chromatin and DNA repair proteins using different BRCT motifs

Background  

By screening a plasmid library for proteins that could cause silencing when targeted to the HMR locus in Saccharomyces cerevisiae, we previously reported the identification of Rtt107/Esc4 based on its ability to establish silent chromatin. In this study we aimed to determine the mechanism of Rtt107/Esc4 targeted silencing and also learn more about its biological functions.     

Type C Niemann-Pick disease. Abnormal metabolism of low density lipoprotein in homozygous and heterozygous fibroblasts

The esterification of cholesterol derived from human low density lipoprotein (LDL) or fetal bovine serum (FBS) was deficient in cultured fibroblasts from subjects with heterozygous and homozygous type C Niemann-Pick (NPC) disease. Failure to significantly esterify LDL-derived cholesterol resulted in abnormal accumulation of predominantly unesterified cholesterol in homozygous NPC fibroblasts. Compared with normal and homozygous fibroblasts, heterozygous NPC fibroblasts synthesized intermediate levels of cholesteryl ester during the initial 6 h of incubation with LDL. The rate of cholesterol esterification in heterozygous cells was normal when measured over a 24-h period of incubation with LDL. In addition to demonstrating a defect in cholesterol esterification, homozygous NPC fibroblasts accumulated more total cholesterol when incubated with LDL or FBS than normal fibroblasts accumulated. When heterozygous NPC fibroblasts were incubated with LDL or FBS, cellular accumulation of cholesterol reached levels that were high-normal or intermediary between levels observed in normal and homozygous NPC fibroblasts. The partial expression of these metabolic errors in the heterozygous genotype relevantly links these errors to the primary mutation of this disorder.     

T cell receptor junctional regions and the MHC molecule affect the recognition of antigenic peptides by T cell clones.

Nine independent pigeon cytochrome c-specific T cell clones were analyzed by using a panel of antigenic peptide analogs presented in association with three allelic IE-encoded MHC glycoproteins. Eight of the T cell clones expressed a TCR composed of a unique alpha- and beta-chain amino acid sequence, and concordantly, each of these T cell clones exhibited a unique Ag specificity. This was true for several clones which differed only in TCR V-J junctional regions. Interestingly, for a given clone, the response to some of the peptide analogs depended to a large extent on the allelic form of the presenting MHC molecule. A simple interpretation of these data would suggest that certain positions of the peptide Ag are most important for Ag-MHC molecule interactions, and that these specific interactions can influence the antigenic epitope recognized by the TCR. We suggest that an antigenic peptide binds to an MHC glycoprotein in a distinct way, but may retain a measure of flexibility.     

Adenosine A2A receptor deficiency attenuates the somnogenic effect of prostaglandin D2

Sleep and Biological Rhythms -