固相反射光度法测定VB12中的痕量钴

研究了以活化硅胶作吸附剂，固相反射吸光光度法测定钴。试验表明，在ＰＨ＝４．０的乙酸钠－乙酸缓冲溶液中，０．０５ｇ活化硅胶对钴－ＰＡＮ〗１－（２－吡啶偶氮）－２－萘酚〖的吸附达最大值，形成的绿色络合物的最大反射吸收波长为６２５ｎｍ，Ｃｏ＾２＋含量在０～６．０μｇ／２５ｍｌ范围内，有良好的线性关系，检出限为８ｎｇ．ｍｌ＾－１，相对标准差为４．９７％。方法用于ＶＢ１２针剂中钴的测定，结果满意。     

孔雀石绿增感聚苯乙炔的光导体

采用电位放电技术研究孔雀石绿（ＭＧ）增感顺式聚苯乙炔（ｃｔ－ＰＰＡ）光导体的光敏性，发现孔雀石绿是顺式聚苯乙炔新的有效增感剂。以Ａｌ／ｃｔ－ＰＰＡ：ＭＧ：ＰＣ（１００：５：１０）（１～１．５μｍ）／ＰＶＫ：ＴＰＡ：ＰＣ（１０：１０：１）（１５～２０μｍ）构成的光导体显示好的光敏性：表面接受电位，Ｖｍａｘ＞７００Ｖ；残余电位，Ｖｍｉｎ＜５０Ｖ；暗衰速率，ＲＤ＜１０Ｖ／ｓ；光衰放电量，△Ｖｔ＞５０％（１．０ｓ）；半衰时间，Ｔ１２＝０．８７Ｓ；感光灵敏度，Ｓ＝２．３×１０－３（１ｘ．ｓ）－１，较未增感ＰＰＡ光导体有较大的提高。ＭＧ对ＰＰＡ为光谱增感     

Rumen bacteria for evaluation of enzymatically changed animal feeds and genetic varieties of fodder plants

Rumen bacteria are used in in vitro incubation methods to predict the apparent digestibility of organic matter in ruminants and pigs. In the method proposed, the gas production during incubation of feeds is measured over different time intervals. Based on multiple regression of data for gas production on the in vivo digestibility of standard samples, accurate predictions can be made (r.s.d.< 2%). For enzyme-treated feeds, the effects of treatment on the degradation of carbohydrates can be estimated from the changes in gas production with time. Ranking of fodder crop varieties can be done on the basis of digestibility, with additional information on the contribution of sugars and the different polysaccharides to the ranking order.     

Essential Oils as In Vitro Ruminal Fermentation Manipulators to Mitigate Methane Emission by Beef Cattle Grazing Tropical Grasses

There is increasing pressure to identify natural feed additives to mitigate methane emissions from livestock systems. Our objective was to investigate the effects of essential oils (EO) extracts star anise (Illicium verum), citronella (Cymbopogon winterianus), clove bud (Eugenia caryophyllus), staigeriana eucalyptus (Eucalyptus staigeriana), globulus eucalyptus (Eucalyptus globulus), ginger (Zingiber officinale), ho wood (Cinnamomum camphora), melaleuca (Melaleuca alternifolia), oregano (Origanum vulgare) and white thyme (Thymus vulgaris) on in vitro methane emissions from four rumen-cannulated Nellore cattle grazing a tropical grass pasture as inoculum donors. The semi-automated gas production technique was used to assess total gas production, dry matter degradability, partitioning factor, ammoniacal nitrogen, short-chain fatty acids and methane production. All essential oils were tested in four doses (0, 50, 250 and 500 mg/L) in a randomized block design, arranged with four blocks, 10 treatments, four doses and two replicates. Within our study, oregano and white Thyme EO reduced net methane production at 250 mg/L, without affecting substrate degradation. Essential oils from oregano and white thyme have the potential to modify ruminal fermentation and suppress rumen methanogenesis without negative effects on feed digestibility, indicating promise as alternatives to ionophores for methane reduction in beef cattle.     

Microbial attack on lignocellulose in the rumen

The microbial population of the rumen consists of many types and species of anaerobic and facultatively anaerobic microorganisms, often at high population densities, living in symbiosis with the animal. The animal is unable to synthesize enzymes capable of digesting the major structural components of plant cell walls (fiber) and relies on the rumen microbes to ferment this material with the generation of volatile fatty acids and microbial cells that the animal can utilize. The crude fiber fraction of ruminant forages consists mainly of cellulose, hemicellulose, and lignin. The rumen contents are rich in organic matter, which has a pH of 5.5–6.9, is maintained at about 39‡C, and has a low redox potential with little free oxygen in the rumen liquor. When plant material enters the rumen, it is invaded by many species of microorganisms, some of which digest certain structural components of the plant cell walls. Measurable digestion of plant cell walls occurs 4–5 h after ingestion by the animal. The rate and extent of digestion is affected by many factors, including the nature and degree of adaptation of the microbial population to the diet, the species of plant and its lignin content, the form in which it is presented to the animal, the amount consumed, and the rate of passage through the rumen. Because the rumen contents are anoxic, there is little degradation of lignin. Some solubilization occurs and lignin-hemicellulose complexes are found in rumen liquor, probably released by cellulolytic and hemicellulolytic microorganisms. One species of bacterium isolated from the rumen preferentially attacked highly lignified cell walls and grew on phenolic acids both aerobically and anaerobically (Akin, 1980), but the abundance and distribution of the species is not known. Phenolic acids are also released and further metabolized in the rumen, and methoxyal groups removed from lignin. Since lignin is covalently bound to cellulose and hemicellulose in the plant cell wall, it probably protects these polysaccharides from microbial attack both physically and chemically. Delignification increases the digestibility of cell wall polysaccharides several-fold. Cellulose may also be shielded from microbial attack by encrusting xylan or xyloglucans (Albersheim, 1975). When plant tissues enter the rumen, they are invaded by both cellulolytic and noncellulolytic microorganisms. Initial invasion is by ciliate protozoa and motile bacteria, followed by phycomycete zoospores and, later, nonmotile bacteria, including cellulolytic species. Some species of ciliate protozoa (e.g.,Epidinium ecaudatum) immediately commence to digest the plant cell walls, but cellulolysis by phycomycete fungi and bacteria is delayed because of preferential metabolism of soluble carbohydrates and the lag before significant attachment of cellulolytic bacteria has occurred. In the predominant cellulolytic rumen bacteria,Ruminococcus albus, R. flavefasciens, andBacteroides succinogenes (Forsberg et al., 1981), adhesion is a prerequisite to cellulolysis because the cellulase enzymes are bound to the cell surface, but some strains ofB. succinogenes also release vesicle-bound enzymes. Cellulases in some species of protozoa (e.g.,Epidinium ecaudatum,Eudiplodinium maggii, andEremoplastron bovis) are now considered to be of protozoon origin (Coleman et al., 1976), but ingested bacteria and adsorbed enzymes may contribute to protozoon cellulolysis. All species of rumen phycomycete fungi examined (Orpin, 1981) have been shown to be cellulolytic and grow on plant cell walls. The cellulase produced by one strain ofNeocallimastix frontalis was associated in part with membranous vesicles released into the medium. Digestion of plant cell walls by the phycomycete fungi is accompanied by the loss of up to 20% of the lignin as a ligninhemicellulose complex. The enzymology of cellulolysis in the rumen is not completely known. It is clear that more than one enzyme is responsible for complete hydrolyses of cellulose to glucose or cellobiose, and endo-1,4-Β-glucanases and Β-1,4-glucosidases have been found in several species of rumen microorganisms. There is also evidence for a ‘swelling factor’ being necessary prior to cellulolysis by some rumen species. All of the cellulolytic rumen microorganisms can also attack, to some degree, the hemicelluloses of the plant cell walls. In some species, cellulase and xylanase activity is associated with the same enzyme complex (e.g.,Bacteroides succinogenes). Other bacteria may attack hemicelluloses, but not cellulose (e.g., some strains ofButyrivibrio fibrisolvens), and others (e.g.,Lachnospira multiparus) digest pectin which allows plant cells to separate and make more cell wall components available to microbial attack. All these organisms act in a consortium resulting in extensive digestion of the plant cell walls.     

In Vitro and In Vivo Digestibility of Soybean,Fish, and Microalgal Oils,and Their Influences on Fatty Acid Distribution in Tissue Lipid of Mice

The digestion rates of microalgal (docosahexaenoic acid, DHA, 56.8%; palmitic acid, 22.4%), fish (DHA, 10.8%; eicosapentaenoic acid, EPA, 16.2%), and soybean oils (oleic, 21.7%; linoleic acid, 54.6%) were compared by coupling the in vitro multi-step and in vivo apparent digestion models using mice. The in vitro digestion rate estimated based on the released free fatty acids content was remarkably higher in soybean and fish oils than in microalgal oil in 30 min; however, microalgal and fish oils had similar digestion rates at longer digestion. The in vivo digestibility of microalgal oil (91.49%) was lower than those of soybean (96.50%) and fish oils (96.99%). Among the constituent fatty acids of the diet oils, docosapentaenoic acid (DPA) exhibited the highest digestibility, followed by EPA, DHA, palmitoleic, oleic, palmitic, and stearic acid, demonstrating increased digestibility with reduced chain length and increased unsaturation degree of fatty acid. The diet oils affected the deposition of fatty acids in mouse tissues, and DHA concentrations were high in epididymal fat, liver, and brain of mice fed microalgal oil. In the present study, microalgal oil showed lower in vitro and in vivo digestibility, despite adequate DHA incorporation into major mouse organs, such as the brain and liver.     

Determination of ytterbium by AES-ICP. Application to samples of biological origin

Summary Ytterbium is used as a marker in studies of digestion physiology in ruminants; its determination has been accomplished by Inductively Coupled Plasma — Atomic Emission Spectroscopy (ICP-AES). An analytical study has been carried out, which includes the evaluation of various emission lines (atomic, ionic). The line at 328.937 nm is proposed for determining Yb, with a limit of detection of 1.68 ×10^–3g ml^–1. The analytical procedure has been applied to the determination of this element in samples of animal fodder, rumen contents and feces.

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Bestimmung von Ytterbium durch AES-ICP. Anwendung auf biologische Proben

     

Limestone doses affecting mineral contents in tropical grass forage

Summary Field trial was performed at the experimental farm of Southeast Embrapa Cattle, São Carlos - SP, Brazil, on a 16 year old Brachiaria decumbens pasture, grown on a distrophic Hapludox (Oxisol), recovered by the use of limestone and fertilizer. The experiments were carried out in random blocks, with 6 replications and 5 treatments. The 100 m² blocks were established in the pasture. Each block received a sequence of limestone doses of 0, 1, 2, 4 and 8 t/ha. The forage samples were taken one year after limestone application on soil surface. Instrumental neutron activation analysis (INAA) followed by gamma-ray spectrometry was the analytical method used to determine mineral contents. The statistical analysis showed a negative linear correlation of Br, Co, Cr, Mn and Zn contents in forage with the limestone doses, while the uptake of Mg was affected in a positive way.     

Plant processing by simultaneous lactic acid fermentation and enzyme hydrolysis

Traditional ensiling of plant material by anaerobic lactic acid fermentation was combined with enzymatic hydrolysis (ENLAC for short) with cell wall degrading enzymes (hemicellulases, cellulases, and pectinases) to increase fiber digestibility or to increase the recovery of cell content from plants. Such findings were made using 0.015% (w/w, wet basis) Phylacell® enzyme preparation by ENLAC of corn and corn-sorghum mixtures, but not of forage grasses. Addition to alfalfa of a mixture of cell wall degrading enzymes, such as NOVO Viscozyme® together with NOVO Celluclast® each at 0.2–1.0% (w/w, wet basis), resulted in more rapid ensiling and improvement of rumen digestibility of silage by 20%. After 20 d of ensiling at 25 °C when the same enzymes were added to alfalfa at the 1.0% level, protein recovery by pressing increased by 35%, β-carotene recovery by 80%, and chlorophyll/xanthophyll recovery by 30%. ENLAC with the same enzymes also increased the recovery of sclareol from muscatel sage by 400%.

     

Effect of the addition of D-xylose on xylanase activity and digestibility of fiber in an artificial rumen

The effect of adding D-xylose at two different levels as a continuous infusion to an artificial rumen was determined with respect to pH, methane production, volatile fatty acid production, fiber digestion, and xylanase activity. No changes in pH, methane production, or fiber digestion were observed as consequences of increased D-xylose concentrations. Although the propionic acid production was slightly raised on addition of D-xylose, the acetic acid production was lowered to the same extent. A low-xylose infusion increased the xylanase activity by 25%, whereas a high-xylose infusion lowered the activity by 17%. It was concluded that D-xylanase activity was not a rate-determining step in fiber degradation in the rumen.     

Anti-Fibrosis Effects of Magnesium Lithospermate B in Experimental Pulmonary Fibrosis: By Inhibiting TGF-βRI/Smad Signaling

Pulmonary fibrosis is a severe and irreversible interstitial pulmonary disease with high mortality and few treatments. Magnesium lithospermate B (MLB) is a hydrosoluble component of Salvia miltiorrhiza and has been reported to have antifibrotic effects in other forms of tissue fibrosis. In this research, we studied the effects of MLB on pulmonary fibrosis and the underlying mechanisms. Our results indicated that MLB treatment (50 mg/kg) for seven days could attenuate bleomycin (BLM)-induced pulmonary fibrosis by reducing the alveolar structure disruption and collagen deposition in the C57 mouse model. MLB was also found to inhibit transforming growth factor-beta (TGF-β)-stimulated myofibroblastic transdifferentiation of human lung fibroblast cell line (MRC-5) cells and collagen production by human type II alveolar epithelial cell line (A549) cells, mainly by decreasing the expression of TGF-β receptor I (TGF-βRI) and regulating the TGF-β/Smad pathway. Further studies confirmed that the molecular mechanisms of MLB in BLM-induced pulmonary fibrosis mice were similar to those observed in vitro. In summary, our results demonstrated that MLB could alleviate experimental pulmonary fibrosis both in vivo and in vitro, suggesting that MLB has great potential for pulmonary fibrosis treatment.