Feed processing parameters and their effects on nursery pig growth performance

A total of 180 nursery pigs (PIC 327 × 1050; initially 27.8 lb) were used in an 18-d study to determine the effects of conditioning parameters and feed form on pig performance. All diets were the same corn, dried distillers grains with solubles (DDGS), and soybean meal-based formulation with different processing parameters used to create the experimental treatments. Treatments included: (1) negative control mash diet, (2) positive control pelleted diet conditioned at 60 rpm, (3) pelleted diet conditioned at 30 rpm and reground, (4) pelleted diet conditioned at 60 rpm and reground, and (5) pelleted diet conditioned at 90 rpm and reground. The different rpm values among treatments represent the time in the conditioner during processing. The lower the rpm value, the longer time feed was in the conditioner. Pigs were weaned and fed a common acclimation diet for 21 d prior to the start of the experiment. Average daily gain and F/G did not differ (P > 0.12) between treatments overall, but ADFI decreased (P = 0.03) for pigs fed the pelleted, positive control diet compared with all other diets. Although no overall treatment effects were significant for ADG or F/G, the experiment was designed more specifically to evaluate treatment differences using preplanned comparisons. When considering preplanned contrasts, we observed that pigs fed mash diets tended to have greater (P = 0.10) ADG than those fed pelleted and reground diets, suggesting that processing may have had a negative influence on feed utilization, a hypothesis that is further supported because pigs fed mash diets tended to have greater (P = 0.06) ADG compared with those fed diets that were heat-processed, regardless of regrinding. Considering these results, it was not surprising that pigs fed mash diets had greater (P = 0.05) ADG and ADFI (P = 0.01) than those fed pelleted diets. When directly comparing diets conditioned at 60 rpm, fed either as whole pellets or reground to mash consistency, pigs fed pelleted diets had improved (P = 0.01) F/G due to lower ADFI (P = 0.004) but similar ADG (P = 0.60). This unexpected negative impact of pelleting on ADG may be due to a negative influence of heat treatment on palatability. The expected improvement in F/G from pelleting (6.8%) was observed but lost when diets were reground to near original mash particle size. This result may indicate that diet form (high-quality pellets vs. mash) affects F/G more than degree of starch gelatinization or other intrinsic factors associated with conditioning ingredients

Codivergence of Mycoviruses with Their Hosts

BACKGROUND: The associations between pathogens and their hosts are complex and can result from any combination of evolutionary events such as codivergence, switching, and duplication of the pathogen. Mycoviruses are RNA viruses which infect fungi and for which natural vectors are so far unknown. Thus, lateral transfer might be improbable and codivergence their dominant mode of evolution. Accordingly, mycoviruses are a suitable target for statistical tests of virus-host codivergence, but inference of mycovirus phylogenies might be difficult because of low sequence similarity even within families. METHODOLOGY: We analyzed here the evolutionary dynamics of all mycovirus families by comparing virus and host phylogenies. Additionally, we assessed the sensitivity of the co-phylogenetic tests to the settings for inferring virus trees from their genome sequences and approximate, taxonomy-based host trees. CONCLUSIONS: While sequence alignment filtering modes affected branch support, the overall results of the co-phylogenetic tests were significantly influenced only by the number of viruses sampled per family. The trees of the two largest families, Partitiviridae and Totiviridae, were significantly more similar to those of their hosts than expected by chance, and most individual host-virus links had a significant positive impact on the global fit, indicating that codivergence is the dominant mode of virus diversification. However, in this regard mycoviruses did not differ from closely related viruses sampled from non-fungus hosts. The remaining virus families were either dominated by other evolutionary modes or lacked an apparent overall pattern. As this negative result might be caused by insufficient taxon sampling, the most parsimonious hypothesis still is that host-parasite evolution is basically the same in all mycovirus families. This is the first study of mycovirus-host codivergence, and the results shed light not only on how mycovirus biology affects their co-phylogenetic relationships, but also on their presumable host range itself

Biotinyl analogues of vasopressin as biologically active probes for vasopressin receptor expression in cultured cells

Biotinyl analogues of [Arg8]vasopressin were synthesized with the biotinyl moiety at position 4. This involved the substitution of 2, 4-diaminobutyric acid (Dab) for Gln4 in [1-deamino-Arg8]vasopressin to give the parent peptide des-[Dab4,Arg8]vasopressin. Two biotinyl analogues with different spacers between the side chain of Dab4 and the biotinyl residue were then prepared and characterized in detail. The analogues retained high binding affinities for the V2-receptor in both bovine kidney membranes and LLC-PK1 renal epithelial cells and for the V2-receptor in rat liver membranes. Both analogues were as potent as [Arg8] vasopressin in stimulating the cAMP-dependent protein kinase and the production of urokinase-type plasminogen activator in LLC-PK1 cells, with concentration dependence consistent with receptor binding affinities. Avidin or streptavidin did not appear to reduce receptor binding or biological activity of the biotinyl analogues. The use of the biotinylated vasopressin analogue des-[Dab-(biotinylamido)hexanoyl4, Arg8]vasopressin together with fluorescein-labeled streptavidin as a fluorescent probe for the V2-receptor in LLC-PK1 cells demonstrated the following: 1) Specific binding of the biotinyl analogue shown by quantitative single-cell fluorescence measurements using the technique of fluorescence microphotolysis; 2) the V2-receptor visualized by fluorescence microscopy; and 3) the expression of the V2-receptor detected by flow cytometry

Detection of a new hormone contact site within the insulin receptor ectodomain by the use of a novel photoreactive insulin

We have used a preparation of soluble human insulin receptor ectodomain and a novel photoreactive, biotinylated derivative of insulin (4-azidosalicyloyl(B1-biocytinyl-B2-lysine)-insulin) to identify a new hormone contact site within the extracellular domain of the insulin receptor. The ectodomain was photoaffinity-labeled and digested to completion with trypsin, and the resulting tryptic fragment was purified by either HPLC or by streptavidin-affinity chromatography. The amino terminus of the fragment was identified as Gly390 within the alpha-subunit. These results suggest that residues that are carboxyl-terminal to the cysteine-rich domain, in addition to previously identified regions within the amino terminus of the alpha-subunit, contribute to the insulin binding site. The implications of these results for the de novo folding of the insulin receptor to constitute the hormone binding site are discussed