Effect of dietary forage to concentrate ratio on volatile fatty acid absorption and the expression of genes related to volatile fatty acid absorption and metabolism in ruminal tissue

The objective of the study was to investigate the fractional rate of volatile fatty acid (VFA) absorption and the expression of genes encoding for transporters and enzymes involved in the absorption and metabolism of VFA in ruminal tissue when cattle were fed high or low concentrate diets. Twelve ruminally cannulated Holstein cows were used in a randomized complete block design. The low concentrate (LC) and high concentrate (HC) diets contained 8 and 64% dietary concentrate (dry matter basis), respectively. Cows were fed their respective diet for at least 28 d, following which data and samples were collected over 6 d. Ruminal pH was measured continuously for 72 h, and the in vivo VFA absorption and passage rates were measured using Co-EDTA and n-valeric acid as markers. Ruminal tissue was collected postslaughter from the ventral sac of the rumen, and gene expression was evaluated using quantitative real-time PCR. Dry matter intake was not affected by treatment, averaging 14.9 kg/d, but cows fed HC had lower mean ruminal pH (6.03 vs. 6.48), and a greater duration (376 vs. 10 min/d) that ruminal pH was <5.8. Ruminal VFA concentration was 24 mM higher for cows fed HC compared with LC; however, the fractional rate of VFA absorption and passage from the rumen was not affected by dietary treatment, averaging 23.4 and 9.6%/h, respectively. The expression of genes encoding for enzymes involved in VFA activation and ketogenesis were not affected by treatment. Cows fed HC tended to have a relative abundance of pyruvate dehydrogenase lipoamide alpha 1 mRNA transcripts that was 1.4 times lower than that of cows fed LC, but other enzymes involved in pyruvate metabolism or regulation of the citric acid cycle were not affected. Collectively, these results suggest that the dietary forage to concentrate ratio does not affect the fractional rate of VFA absorption in vivo, but potentially alters energy metabolism in ruminal tissue.

Board-invited review: the biology and regulation of preadipocytes and adipocytes in meat animals

The quality and value of the carcass in domestic meat animals are reflected in its protein and fat content. Preadipocytes and adipocytes are important in establishing the overall fatness of a carcass, as well as being the main contributors to the marbling component needed for consumer preference of meat products. Although some fat accumulation is essential, any excess fat that is deposited into adipose depots other than the marbling fraction is energetically unfavorable and reduces efficiency of production. Hence, this review is focused on current knowledge about the biology and regulation of the important cells of adipose tissue: preadipocytes and adipocytes.

Mature adipocytes may be a source of stem cells for tissue engineering

Adipose tissue contains a large portion of stem cells. These cells appear morphologically like fibroblasts and are primarily derived from the stromal cell fraction. Mature (lipid-filled) adipocytes possess the ability to become proliferative cells and have been shown to produce progeny cells that possess the same morphological (fibroblast-like) appearance as the stem cells from the stromal fraction. A closer examination of mature adipocyte-derived progeny cells may prove to be an emerging area of growth/metabolic physiology that may modify present thinking about adipose tissue renewal capabilities. Knowledge of these cells may also prove beneficial in cell-based therapies for tissue repair, regeneration, or engineering.

Investigating the Effects of Commercial Probiotics on Broiler Chick Quality and Production Efficiency

A study was undertaken to test the effect of 2 commercially available probiotics on the production efficiency of broiler chickens hatched from the same breeder flock at 3 different ages (28, 43, and 57 wk). At each of the 3 breeder flock ages, 1,600 broiler chickens were hatched and randomly allocated to 1 of 4 treatments: 1) no probiotics (control), 2) probiotic 1 administered in the drinking water, 3) probiotic 1 administered as a spray, and 4) probiotic 2 administered in the feed. A coccidiostat was included in the feed, but no other antimicrobial agents were given. Broilers were then reared on straw litter in identical floor pens for a period of 6 wk. There were no significant differences in broiler BW, feed conversion, or mortality between the probiotic treatments and the control group in any of the trials. The 43-wk-old breeder flock had the highest fertility and hatchability and the lowest percentage of chicks culled at hatching. Throughout the broiler production period, the broilers from the 43- and 57-wk-old breeder flocks had higher BW and weight gains than the broilers produced at 28 wk of breeder flock age. Broiler feed conversion over the 6-wk production period decreased as the breeder flock aged. Probiotics had no effect on chick quality or production efficiency in broilers produced by the breeder flock ages examined.

Isolation and Evaluation of Nonsiderophore Cyclic Peptides from Marine Sponges

The world's oceans are iron-deficient environments and there is little knowledge available regarding iron uptake by marine sponges. To understand iron-related biofunctions in marine organisms, iron-binding natural compounds from marine sponges were investigated. Here we reported a natural compound haliclonamide A and its analogue haliclonamide B were isolated from the marine sponge Haliclona sp. and their structures were investigated by spectroscopic analysis. The structure of haliclonamide A was determined to consist of novel cyclic peptides containing oxazole and methyloxazoline rings. Mass spectra revealed that these two compounds formed a 1:1 stable complex with trivalent iron but not with divalent iron. EPR analysis showed that these compounds will bind with Fe(III) and Cr(III) specifically, but will not bind to other cation ions such as Cu2+, Zn2+, Co2+, Ni2+, Al3+, and Ti3+. The binding constant of compound-iron complex was 10(19) which is lower than the binding constant of siderophores. The Fe(III) concentration in this sponge tissue was shown to be 10 and 100 times higher than the other sponge tissues and seawater. This indicated the sponge Haliclona sp. may possibly uptake iron through nonsiderophore metal-binding peptides haliclonamides A and B. It also suggests that iron uptake activity of marine organisms may occur through nonsiderophore metal-binding peptides in natural ocean.

Effect of exogenous siderophores on iron uptake activity of marine bacteria under iron-limited conditions

More than 60% of species examined from a total of 421 strains of heterotrophic marine bacteria which were isolated from marine sponges and seawater were observed to have no detectable siderophore production even when Fe(III) was present in the culture medium at a concentration of 1.0 pM. The growth of one such non-siderophore-producing strain, alpha proteobacterium V0210, was stimulated under iron-limited conditions with the addition of an isolated exogenous siderophore, N,N'-bis (2,3-dihydroxybenzoyl)-O-serylserine from a Vibrio sp. Growth was also stimulated by the addition of three exogenous siderophore extracts from siderophore-producing bacteria. Radioisotope studies using (59)Fe showed that the iron uptake ability of V0210 increased only with the addition of exogenous siderophores. Biosynthesis of a hydroxamate siderophore by V0210 was shown by paper electrophoresis and chemical assays for the detection of hydroxamates and catechols. An 85-kDa iron-regulated outer membrane protein was induced only under iron-limited conditions in the presence of exogenous siderophores. This is the first report of bacterial iron uptake through an induced siderophore in response to exogenous siderophores. Our results suggest that siderophores are necessary signaling compounds for growth and for iron uptake by some non-siderophore-producing marine bacteria under iron-limited conditions.

Bacterial growth stimulation with exogenous siderophore and synthetic N-acyl homoserine lactone autoinducers under iron-limited and low-nutrient conditions

The growth of marine bacteria under iron-limited conditions was investigated. Neither siderophore production nor bacterial growth was detected for Pelagiobacter sp. strain V0110 when Fe(III) was present in the culture medium at a concentration of <1.0 microM. However, the growth of V0110 was strongly stimulated by the presence of trace amounts of exogenous siderophore from an alpha proteobacterium, V0902, and 1 nM N-acyl-octanoylhomoserine lactone (C(8)-HSL), which is known as a quorum-sensing chemical signal. Even though the iron-binding functionality of a hydroxamate siderophore was undetected in the supernatant of V0902, a hydroxamate siderophore was detected in the supernatant of V0110 under the above conditions. These results indicated that hydroxamate siderophore biosynthesis by V0110 began in response to the exogenous siderophore from V0902 when in the presence of C(8)-HSL; however, C(8)-HSL production by V0110 and V0902 was not detected. Direct interaction between V0902 and V0110 through siderophore from V0902 was observed in the dialyzing culture. Similar stimulated growth by exogenous siderophore and HSL was also observed in other non-siderophore-producing bacteria isolated from marine sponges and seawater. The requirement of an exogenous siderophore and an HSL for heterologous siderophore production indicated the possibility that cell-cell communication between different species was occurring.

Synthesis, topoisomerase I inhibitory activity and in vitro cytotoxicity of camptothecin derivatives bearing five-membered heterocycle containing 10-substituents

A series of new camptothecin derivatives bearing certain five-membered heterocycles was synthesized and evaluated for in vitro cytotoxic activity. The cytotoxicity results show that camptothecin derivatives bearing pyrrole and thiophene rings were more potent than camptothecin, whereas those bearing furan were less active than camptothecin. Agarose gel electrophoresis shows different inhibitory activities of the camptothecin analogs towards topoisomerase I DNA cleavage. The pyrrole-containing compounds inhibit topoisomerase I DNA cleavage more strongly than camptothecin, but the thiophene and furan compounds do not show any inhibitory activities for DNA cleavage functions of topoisomerase I. Polyacrylamide gel sequencing electrophoresis shows that the pyrrole compounds induce single-strand breaks after incubating with a labeled DNA fragment. The results suggest that the pyrrole compounds fit the compound-enzyme-DNA complex better than camptothecin and the other analogs.

Enhanced DNA alkylation activities of Hoechst 33258 analogues designed for bioreductive activation

A series of analogues of Hoechst 33258, designed to be subject to bioreductive activation, were synthesized, and interactions between these compounds and pBR322 DNA were investigated. Compounds containing a quinone group reacted with DNA via two possible pathways in the presence of reductants NADH or NADPH: radical cleavage and DNA alkylation. The corresponding dimethoxy compounds, which are not subject to reduction, showed very weak DNA binding ability. The strength of alkylation reaction of the quinone derivatives is related to leaving group ability. Furthermore, the quinone compounds preferentially alkylate DNA at 5'-CG and TG sequences rather than at the AT sites preferred as binding sites of Hoechst 33258.

Specific interaction with guanine residues of Z-form DNA by bleomycin-nickel(III) complex

The Ni(III) complex of bleomycin (BLM) reacts with guanine residues of the oligomer duplex only under high salt condition (4.5 M NaCl) where the (dC-dG)6 sequence exists as the isolated Z-form segment. In addition, the (dC-dG)n inserts were subcloned into a plasmid so that reactivity of the BLM-Ni(III) complex with restriction fragments could be examined. Results are reported for two fragments: an EcoRI-DdeI fragment in which the (dC-dG)n insert is flanked at the 5' end by a segment of B-DNA and a HindIII-DdeI fragment in which the (dC-dG)n fragment is embedded at both ends by stable B-DNA forming segments. The BLM-Ni(III) complex does not bind to (dC-dG)5 sequence of pBRZ10 DNA fragment under any conditions, but to several guanine residues of (dC-dG)8 and (dC-dG)12 sequences of pBRZ16 and pBRZ24 DNA fragments in 4.5 M NaCl solution. In the fragments of pBRZ16 and pBRZ24 DNAs, the BLM-Ni(III) complex reacts with most of guanine bases of (dC-dG)8 and (dC-dG)12.

Guanine-specific binding by bleomycin-nickel(III) complex and its reactivity for guanine-quartet telomeric DNA

Bleomycin-Ni(III) [BLM-Ni(III)] complex, generated from oxidation of the corresponding BLM-Ni(II) complex with Ir(IV) or oxone, binds to single-stranded DNA and causes strand scission at specific guanine sites. In the telomeric-like oligodeoxynucleotide d(T2G4)4, the cleavage by the BLM-Ni(III) complex occurs preferentially at positions G-9 and G-15 in loop regions. By contrast, this Ni(III) complex does not induce cleavage of G-quartet d(G4T4G4)2, which contains no loop guanines, ESR evidence supports that binding of the N-7 position of guanine occurs axially to the Ni(III) center in BLM. The present results provide interesting insights into Ni-BLM chemistry.

Cleavage of yeast tRNA(phe) with Ni(III) and Co(III) complexes of bleomycin

The BLM-Ni(III) complex preferentially cleaves guanine residues at D loop and anticodon loop of yeast tRNA(phe) by aniline treatment, whereas the BLM-Co(III) complex degrades certain 5'-AN sites of the minor groove region after irradiation of UV light. These cleavage features are clearly different from that of the BLM-Fe(II) complex.

[The diagnostic value of M-mode, 2D, and Doppler echocardiography in incomplete endocardial cushion defect]

The diagnostic value of ultrasonography in cases with incomplete endocardial cushion defect which has been verified by subsequent operation was studied. By the M-mode ultrasound examination an enlarged right ventricle, a narrowed outflow tract of left ventricular and an abnormal pattern of mitral value were shown. By the aid of 2-DE its diagnostic accuracy in this disease was almost 100%. Characteristically the ostium primum (atrial septal) defect and anterior mitral cleft were demonstrated. And by pulsed Doppler the signs of mitral regurgitation and the spectral features of atrial shunt could be found. Therefore, it is proposed that ultrasonographic examination could readily take the place of traumatic angiocardiography in the diagnosis of this disease.