Fermentation of Maize Bran, Oat Bran, and Wheat Bran by Bacteroides ovatus V975

Bacteroides ovatus is a Gram-negative obligate anaerobe that was isolated from the human colon and is capable of utilizing xylan. The objective of this study was to evaluate the ability of B. ovatus V975 to digest maize bran, oat bran, and wheat bran as well as the isolated cell walls from each bran source. Strain V975 was incubated in basal medium that contained either 0.1 or 0.3 g of each bran or each bran cell wall for 0, 24, 48, and 72 h. Acetate and succinate were the main products detected from each fermentation; however, less of each end product was produced from the isolated cell walls than from each bran. More of the oat bran was digested (in vitro dry matter disappearance = 74.8%) during the 72 h incubation than any other bran source. While each bran contained arabinose and xylose, more glucose, galactose, and mannose were utilized by strain V975 during the 72-h incubation than either pentose sugar. Compared with each bran, the bran cell walls had lower concentrations of most sugars, and more glucose than any other sugar was utilized by strain V975. These results suggest that strain V975 preferentially utilizes glucose, galactose, and mannose in each bran, while glucose is the main sugar fermented in bran cell walls. Received: 19 June 1997 / Accepted: 31 July 1997     

Deoxyribonuclease Activity in Selenomonas ruminantium, Streptococcus bovis, and Bacteroides ovatus

Six Selenomonas ruminantium strains (132c, JW13, SRK1, 179f, 5521c1, and 5934e), Streptococcus bovis JB1, and Bacteroides ovatus V975 were examined for nuclease activity as well as the ability to utilize nucleic acids, ribose, and 2-deoxyribose. Nuclease activity was detected in sonicated cells and culture supernatants for all bacteria except S. ruminantium JW13 and 179f sonicated cells. S. ruminantium strains were able to utilize several deoxyribonucleosides, while S. bovis JB1 and B. ovatus V975 showed little or no growth on all deoxyribonucleosides. When S. ruminantium strains 5934e, 132c, JW13, and SRK1 were incubated in medium that contained 15 mm ribose, the major end products were acetate, propionate, and lactate. S. ruminantium 5521c1 and S. bovis JB1 did not grow on ribose, and none of the S. ruminantium strains or S. bovis JB1 grew on 15 mm 2-deoxyribose. In contrast, B. ovatus V975 was able to grow on ribose and 2-deoxyribose. In conclusion, all S. ruminantium strains, S. bovis JB1, and B. ovatus V975 had nuclease activity. However, not all bacteria were able to utilize deoxyribonucleosides, ribose, or 2-deoxyribose. Received: 9 February 2000 / Accepted: 27 March 2000     

Starch Utilization by Bacteroides ovatus Isolated from the Human Large Intestine

Starch supported growth of continuous cultures of Bacteroides ovatus when this carbohydrate provided the sole source of carbon and energy. Inducible amylase and α-glucosidase activities were inversely related to dilution rate in starch-limited and starch-excess chemostats over the dilution rate (D) range D = 0.03/h to D = 0.20/h, and were partly repressed during growth under conditions of starch-excess. Preparative isoelectric focusing of B. ovatus cytoplasmic extracts indicated the existence of three distinct starch-hydrolyzing enzymes. Incubation of active fractions from the isoelectric focusing cell with maltose and a variety of low-molecular-weight oligosaccharides (maltotriose, maltotetraose, maltopentaose, maltohexaose, maltoheptaose) identified a single amylase activity, an enzyme with combined β-amylase and glucoamylase/α-glucosidase properties, and also a possible pullulanase. The ability of B. ovatus to synthesize several starch-hydrolyzing enzymes with different specificities and activities may confer a significant competitive advantage to this organism in the colonic ecosystem. Received: 14 August 1996 / Accepted: 29 October 1996     

Bloodmeal digestion in the midgut of Phlebotomus papatasi and Phlebotomus langeroni

Abstract. Bloodmeal digestion in midguts of the sandflies Phlebotomus papatasi and Phlebotomus langeroni (Diptera: Psychodidae) was investigated in optimized assays to detect general protease, trypsin and aminopeptidase activities using synthetic substrates. Optimal activity occurred at pH 8-9 for all enzymes examined in both species. Protease activity peaked at 24-34h post human bloodmeal in midguts of P.papatasi and 34-48h in P'.langeroni; all endo- and exoprotease activities were completed by 50 h in P.papatasi compared to 72 h in P. langeroni. Hydrolysis of two chymotrypsin substrates was <2% of trypsin activity in both species. Aminopeptidase activity was associated mainly with the midgut wall, whereas trypsin activity was confined to the midgut lumen. A feature of digestion in P.langeroni was the high level of aminopeptidase recorded within 10h of the bloodmeal.     

Effect of Aloe vera whole leaf extract on short chain fatty acids production by Bacteroides fragilis, Bifidobacterium infantis and Eubacterium limosum

Aims: To investigate the effect of Aloe vera whole leaf extract on pure and mixed human gut bacterial cultures by assessing the bacterial growth and changes in the production of short chain fatty acids. Methods and Results: Bacteroides fragilis, Bifidobacterium infantis, and Eubacterium limosum were incubated with Aloe vera extracts [0%, 0·5%, 1%, 1·5% and 2%; (w/v)] for 24 and 48 h. Short chain fatty acids production was measured by gas chromatography/mass spectrometry analyses. A significant linear increase in growth response to Aloe vera supplementation was observed at 24 h for each of the bacterial cultures; however, only B. infantis and a mixed bacterial culture showed a significant positive linear dose response in growth at 48 h. In pure bacteria cultures, a significantly enhanced dose response to Aloe vera supplementation was observed in the production of acetic acid by B. infantis at 24 h and of butyric acid by E. limosum at 24 and 48 h. In the mixed bacterial culture, the production of propionic acid was reduced significantly at 24 and 48 h in a dose‐dependent fashion, whereas butyric acid production showed a significant linear increase. Conclusions: The results indicated that Aloe vera possessed bacteriogenic activity in vitro and altered the production of acetic, butyric and propionic acids by micro‐organisms selected for the study. Significance and Impact of the Study: The results of the study suggest that consumption of a dietary supplement, Aloe vera, may alter the production of short chain fatty acids by human intestinal microflora.     

Introgressive hybridization of Senecio hercynicus and S. ovatus (Compositae,Senecioneae) along an altitudinal gradient in Harz National Park (Germany)

Introgressive hybridization of Senecio hercynicus and S. ovatus (Compositae, Senecioneae) was studied in a hybrid zone on the southern slopes of Mt Brocken (Harz Mountains, Germany). A total of 415 plants representing 10 stands along an altitudinal gradient were investigated using multivariate statistical analyses of morphological characters and molecular markers (random amplified polymorphic DNA[RAPD]). Both types of traits detected pure S. hercynicus stands on the summit plateau, pure S. ovatus stands at the lowest elevations, and hybrid swarms at intermediate elevations. While morphological and molecular patterns coincided, some individuals in hybrid stands combined morphological patterns typical of S. ovatus with RAPD patterns typical of S. hercynicus, and vice versa. In general, introgression was symmetrical within stands, though one stand combined S. ovatus characters with the glandular hair typical for S. hercynicus, and two stands combined a S. hercynicus typical RAPD genotype with morphological characters shifted towards S. ovatus. Because pure stands of S. hercynicus occurred only on the summit plateau of Mt Brocken, and markers typical for S. ovatus were detectable in stands up to 1040 m a.s.l., future fusion or assimilation of the rare form, S. hercynicus, by the more widespread S. ovatus appears possible at Mt Brocken.     

Temporal analysis of 16 STR loci in human blood drawn from two culicid mosquitoes cultured at different temperatures

Female mosquitoes feed on human blood, which can be collected to analyze human short tandem repeat (STR) sequences; these are specific to each human individual. Analysis of STRs might help in identification of a person found near a crime scene. Aedes aegypti and Culex pipiens mosquitoes fed on human blood were cultured at 18°C or 40°C (median temperature for summer and winter time in Riyadh governorate, Saudi Arabia) for 3, 6, 12, 24, 48 and 72 h. In A. aegypti, human DNA concentration was reduced with time at both temperatures. At 18°C, we obtained full STR profiles up to 48 h post feeding on human blood while none of the 16 loci were obtained at 72 h. At 40°C, we missed six sites at 12 h after blood sucking, 12 at 24 h, and 15 at 48 h and 72 h. In C. pipiens cultured at 18°C, full profiles were developed up to 48 h following blood feeding while we could not amplify five sites at 72 h. At 40°C, mortality among females was 50% at 24 h and 100% at both 48 h and 72 h; however, we had full profiles in all samples including dead insects. This research addressed the possibility of using mosquitoes in forensic research by DNA genotyping by changing the mosquito culturing temperature and mosquito genus. Our findings proved that different types of mosquito change the temporal pattern of STR analysis and showed that the mosquito culturing temperature affects the integrity of DNA for STR analysis.     

Escherichia coli-Anacystis nidulans plasmid shuttle vecotrs containing the PL promoter from bacteriophage lambda

The gene encoding xylanase activity in the ruminal bacteriumBacteroides ruminicola D31d was cloned and expressed inEscherichia coli with the plasmid vector pUC18. The gene was isolated on a 4.7-kilobase pair partialPstI genomic DNA fragment. The xylanase activity expressed inE. coli was cell associated and could degrade both oatspelt xylan and Remazol Brilliant Blue-xylan. The xylanase did not have detectable activity against carboxymethylcellulose. Utilization of an endogenous promoter byE. coli was indicated by expression of xylanase activity after subcloning of the insert into pBR322 in opposite orientations. TheB. ruminicola D31d xylanase gene was compared by Southern hybridization analyses with xylanase genes cloned fromB. ruminocola 23 andB. ovatus V975, a human intestinal isolate. The D31d xylanase gene did not cross-hybridize with either of the other two genes. In addition, the 23 xylanase gene did not cross-hybridize with the other two genes according to the same technique. These results indicate that the three cloned genes do not share a high degree of genetic similarity, despite the similar enzymatic activities. This is the first study to compare cloned genes from ruminal and colonicBacteroides species.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Assessment of a brown midrib (BMR) mutant gene on the nutritive value of sudangrass using in vitro and in vivo techniques

The brown midrib (BMR) gene has been reported to reduce the lignin concentration in plants, which contributed to increased fiber digestion in ruminants. Three studies were completed to compare the digestibility of a BMR mutant of sudangrass (sorghum bicolor subsp. Drummondii) versus a non-BMR (‘Piper’) variety when included in diets fed to sheep (Study 1), to complete a rumen in vitro assessment of sheep and lactating cow diets (Study 2), and to compare digestibility when included in the diet fed to lactating dairy cows (Study 3). Four wether sheep were used in a 2 × 2 Latin square experiment (Study 1) with total fecal collection to determine total tract apparent digestibility of pelleted Piper (P) and BMR (P-BMR) sudangrass hays. Forage pellets consisted of either P-BMR or P hay with added urea to meet the maintenance crude protein (CP) requirement of the sheep. Digestibility of organic matter (OM; P<0.01), dry matter (DM; P<0.01), acid detergent fiber (ADF; P<0.05), and neutral detergent fiber (aNDFom; P<0.07) was higher for P-BMR than P sudangrass. In vitro rumen digestibility of aNDFom using cattle rumen fluid was higher at 24 (P<0.01), 48 (P<0.01) and 72 h (P<0.01) of fermentation for P-BMR versus P (Study 2). Four lactating Holstein dairy cows (251 ± 30 days in milk) and fitted with ruminal and duodenal cannulae were used in a 4 × 4 Latin square experiment. Total mixed rations (TMR) contained 180 g/kg DM shredded sudangrass hay and 180 g/kg sliced alfalfa hay, but the proportion of P to P-BMR sudangrass varied as 100:0, 66:34, 34:66, or 0:100. Yields of milk and milk protein were highest at the 66:34 level (Quadratic: P=0.06 and 0.07, respectively), but composition of milk fat, protein and lactose, as well as DM intake, did not differ (Study 3), probably because forestomach and total tract apparent digestion of aNDFom and OM did not differ due to sudangrass source.     

Enzymological Characterization of Atm,the First Laccase from Agrobacterium sp. S5-1, with the Ability to Enhance In Vitro digestibility of Maize Straw

Laccase is an enzyme that catalyzes oxidation of phenolic compounds, diamines and aromatic amines. In this study, a novel laccase-like gene (atm) in a ligninolyitic isolate Agrobacterium sp. S5-1 from soil humus was identified and heterologously expressed in Escherichia coli. Atm exhibited its maximal activity at pH 4.5 and at 50°C. This enzyme was tolerant to high temperature, a broad range of pH, heavy metal ions (Co³⁺, Mn²⁺, Cu²⁺ and Ni²⁺, 20 mM) and all tested organic solvents. Furthermore, Atm significantly (p<0.05) increased dry matter digestibility of maize straw from 23.44% to 27.96% and from 29.53% to 37.10% after 8 or 24 h of digestion and improved acid detergent fiber digestibility from 5.81% to 10.33% and from 12.80% to 19.07% after 8 or 24 h of digestion, respectively. The combination of Atm and fibrolytic enzymes significantly (p<0.05) enhanced neutral detergent fiber digestibility from 19.02% to 24.55% after 24 h of digestion respectively. Results showed treatment with Atm effectively improved in vitro digestibility of maize straw, thus suggesting that Atm has an application potential for bioconversion of lignin rich agricultural byproducts into animal feed and cellulosic ethanol.     

Digestibility of chitin in cod,Gadus morhua,in vivo

Sixteen cod,Gadus morhua (L.), were individually fed a single ration of shrimps,Crangon allmanni. Four fish were killed and examined 6, 12, 24 and 48 h after the fish had been fed. Chitinase activities were measured in the extracts of stomach contents, stomach tissue, pyloric caecae, intestinal contents and intestinal tissue. The level of enzyme activity in different parts of the digestive tract was shown to be dependent on the phase of the digestive process. High concentrations of the chitin degradation product N-acetyl-D-glucosamine were determined in the stomach and in the intestinal contents. Based on the chitin concentration in the food organisms and the individual food uptake, the amount of chitin consumed by each fish could be calculated. Only up to 9% of the ingested chitin was recovered from the intestinal contents of the fish at any given time after feeding (6, 12, 24 and 48 h). In addition, only 2.4% of the chitin consumed with the food could be recovered in the collected faeces of the fish. The 4 cod killed 48 h after feeding had completely emptied their stomach. Chitin digestion in these fish was calculated to have been 90%.     

Enhanced production of penicillin V acylase from Streptomyces lavendulae

At 28 °C, Streptomyces lavendulae produced high levels of penicillin V acylase (178 IU/l of culture) when grown on skim milk as the sole nutrient source for 275 h. The enzyme showed catabolite repression by glucose and was produced in the stationary phase of growth. Penicillin V was a good inducer of penicillin V acylase formation, while phenoxyacetic acid, the side-chain moiety of penicillin V, did not alter enzyme production significantly. The enzyme was stable between pH 6 and 11 and at temperatures from 20 °C to 55 °C. This extracellular enzyme was able to hydrolyse natural penicillins and unable to hydrolyse penicillin G. Received: 22 March 1999 / Received revision: 16 June 1999 / Accepted: 20 June 1999     

Fecundity, longevity and establishment of Otiorhynchus sulcatus (Fabricius) and Otiorhynchus ovatus (Linnaeus) (Coleoptera: Curculionidae) from the Pacific North-west of the United States of America on selected host plants

1 The fecundity, longevity and establishment of Otiorhynchus sulcatus and Otiorhynchus ovatus from the Pacific North‐west U.S.A. was studied on five selected host plants: Picea abies‘Nidiformis’, Picea glauca‘Conica’, Taxus baccata, Rhododendron catawbiense‘Boursault’ and Fragaria×ananassa‘Totem’. 2 Teneral adults were used to study adult longevity and reproductive success. Leaves of these host plants were used for sustenance for 9 months. Larval establishment was studied by infesting potted host plants with eggs. 3 Fragaria×ananassa‘Totem’ produced the longest survival, shortest preoviposition time, the greatest number of eggs, and the highest fertility for adults of both species. Picea spp. were not good adult hosts for O. sulcatus. Taxus was a good adult host for O. sulcatus, but was a nonhost for adults and larvae of O. ovatus. 4 Adult hosts did not affect preoviposition time or egg viability with O. ovatus adults. With O. sulcatus, preoviposition time was greatly increased and egg viability was < 50% on Picea spp. 5 The best larval host was F.×ananassa‘Totem’ for O. sulcatus and P. glauca‘Conica’ for O. ovatus. Rhododendron was a poor larval host for both species. 6 When all of the studies on these two pests are considered, O. sulcatus appears to have varying host preferences from among its many geographical areas of occurrence whereas O. ovatus has a more universal host selection.     

The effects of physical factors on survival of stored food mites

The effects of physical factors (low barometric pressure, high and low temperature, light) on survival of stored food mites (Acaridae: Acarus siro L., Tyrophagus putrescentiae (Schrank), Aleuroglyphus ovatus (Troupeau), Caloglyphus berlesei (Michael); Glycyphagidae: Glycyphagus domesticus De Geer; Carpoglyphidae: Carpoglyphus lactis (L.); Pyroglyphidae: Dermatophagoides pteronyssinus (Troupeau); Cheyletidae: Cheyletus eruditus (Schrank) were studied. C. lactis was the most resistant species-most specimens (85%) of this species survived the longest exposure (96 h) to the lowest pressure (95 mm Hg) tested. It showed 100% mortality only after 80 h exposure to -15°C and it was able to withstand 45°C for about 1 h. Mites from the family Acaridae were killed by low pressure of 95 mm Hg after an exposure of only 48 h and after 1 h exposure to -15°C. Constant light has unfavourable effects on development and reproduction of the flour mite, A. siro.Our results may have some practical implications. Vacuum of 190 mm Hg will protect the food against the mites. Also low temperature -15°C could be used to control mites in seed.     

Cytogenetic studies on natural intergeneric hybridization inAster alliances

The karyotype and meiosis of the 12-ploid plants—one of the offspring of the natural F₁ hybrid (Aster ageratoides subsp.ovatus (2n=36) ×Kalimeris incisa (2n=72), 2n=72)—were examined. The 2n=108 chromosomes of the 12-ploids were found to consist of 18 large chromosomes and 90 small chromosomes. In meiosis of the PMCs of the 12-ploid, chromosome configurations of 3_III+46_II+7_I, 2_III+48_II+6_I and 3_III+47_II+5_I were observed. All the univalents and trivalents were small, and among the 46–48 bivalents nine were large and the remaining 37–39 were comparatively small. The large bivalents were found to represent autosyndetic pairings, and the small bivalents and trivalents were probably formed by autosyndetic pairings. The large chromosomes of the 12-ploids were found to coincide with the large chromosomes ofovatus, and the 90 small chromosomes to correspond to small chromosomes ofovatus andK. incisa. The 12-ploids were concluded to have been produced by a fusion of an unreduced gamete of the F₁ plant and a reduced gamete ofK. incisa which was growing in proximity to the F₁s. Thus the 12-ploids were regarded to be an amphidiploid having 36 chromosomes ofovatus and 72 chromosomes ofK. incisa.     

Extrinsic vs. intrinsic food shortage and the strength of feeding links: effects of density and food availability on feeding rate of Hyphydrus ovatus

Summary We use field and laboratory experiments to determine whether Hyphydrus ovatus, a predatory aquatic beetle, is food limited, and whether any food shortage results from depletion of prey by these predators (intrinsic food shortage) or is independent of predation by these beetles (extrinsic food shortage). In the laboratory, differences in feeding rate influence body fat content, thus making fat content a useful index of recent feeding history. H. ovatus collected during the breeding season have fat contents significantly greater than those of H. ovatus starved for 25 days, but not significantly different from those of H. ovatus fed ad libitum for 25 days, indicating that natural feeding rates are near the maximum possible. H. ovatus confined at a density 60 times greater than natural show reduced fat content and feeding rate relative to natural, indicating that at very high densities H. ovatus is capable of depleting its prey. Addition of supplemental natural prey (primarily Cladocera) to experimental enclosures resulted in an order of magnitude increase in prey availability, and a significant increase in fat content and feeding rate of confined H. ovatus. Adults of this species do not appear to be food limited during the breeding season, and extraordinarily high densities of adults seem to be necessary to produce intrinsic food shortage. These results suggest that feeding links between H. ovatus an its principal prey do not have major effects on population dynamics under typical field conditions, and call into question the assumption that closely coupled predator-prey interactions are the sole explanation for observed food-web patterns.     

Collagenase activity in the normal rat myocardium

Summary Fibrillar collagen in the myocardium provides a supportive framework for myocytes and capillaries. Disruption of this organized framework has been observed in certain pathological states. Collagen degradation is primarily mediated by the specific enzyme collagenase, which has been found to exist in various tissues including the myocardium. In this report we describe a method that detects collagenase activity in sections of cardiac tissue. This method is on the basis of degradation of collagen by collagenase on one hand and the visualization of disrupted collagen fibers by immunofluorescence on the other. Frozen rat heart secctions were incubated under optimal conditions for collagenase activity (37°C in the presence of 0.1 M calcium at pH 7.4) for 24 h and 48 h. Subsequently, immunofluorescence staining with antibody to type I collagen was performed and the collagenous structures were visualized by immunofluorescence light microscopy. As control, untreated rat heart sections and sections incubated in the absence of calcium were similarly treated with antibody. After the 24 h of incubation, we found no change in the structural integrity of collagen fibers. Marked disruption of the type I collagen fibers was observed 48 h after incubation. No evidence of collagen fiber disruption was found in control sections. Experiments with exogenous collagenase resulted in similar collagen fiber disruption in the frozen rat heart sections. We conclude that the disruption of collagen type I fibers after 48 h of incubation, under optimal conditions for collagenolytic digestion, is. the result of collagen degradation by intrinsic collagenase of the myocardium.     

Livestock Tick Predation by Chickens: The Rate of Digestion of Ticks in the Alimentary Tract of Chickens

Research on the predation of ticks by chickens is required to establish the potential rôle of chickens as biological control agents for ticks. In the present study, 26 local chickens were allowed to feed in groups of two or three for 1 hour on a meal containing adult unengorged Rhipicephalus appendiculatus and Amblyomma variegatum and slaughtered thereafter at different intervals ranging from 11 min to 24 h. The contents of the digestive tracts of the chickens were carefully examined under a dissecting microscope to determine the state of digestion of the ingested ticks.

All ticks found in the crop were not digested and a few A. variegatum were attached to the crop wall and were found dead. The gizzard contained partially and completely digested ticks while tick remnants were predominant in the small intestine. It was concluded that most of the digestion of tick proteins takes place in the small intestine. It was also concluded that, although the digestion rate of ticks varies in individual chickens, all ticks digested in a meal should have been completely digested and absorption of the tick nutrients should have started within 21–24 h although this could have been accomplished as early as 9 h by chickens with fast digestion rates.     

In sacco rumen disappearance of condensed tannins, fiber, and nitrogen from herbaceous native Texas legumes in goats

Condensed tannins (CT) can play a role in rumen protein and fiber degradability, especially in legumes high in CT. In order to better understand their potential role in ruminant nutrition, three legume species native to Texas, Acacia angustissima var. hirta (prairie acacia) (288.0 g/kg neutral detergent fiber (NDFom), 40.9 g/kg N), Desmodium paniculatum (panicled tick-clover) (479.7 g/kg NDFom, 24.8 g/kg N), and Lespedeza procumbens (trailing bush-clover) (401.0 g/kg NDFom, 21.7 g/kg N) were studied to determine in sacco disappearance rates of key nutritional components compared to that of Medicago sativa (alfalfa) (226.8 g/kg NDFom, 34.6 g/kg N). Herbage was incubated in rumen-cannulated goats fed a basal diet of Sorghum bicolor×S. sudanense (sorghum-Sudan) hay, with disappearance measured at 0, 4, 8, 16, 28, 48 and 96 h. Among the native legumes, the highest CT concentrations were measured in prairie acacia (263 g CT/kg DM foliage) and the lowest (120 g CT/kg DM) in trailing bush-clover. The lowest concentrations of acid detergent fiber (ADFom), NDFom, and sulfuric acid lignin (lignin(sa)) were measured in prairie acacia, the first two fractions being comparable to alfalfa. Proportion remaining was calculated for CT, ADFom, lignin(sa), NDFom, and N for 0, 24 and 48 h of rumen incubation. Disappearance parameters were measured for ADFom, lignin(sa), NDFom and N for the three native legumes and compared to alfalfa. Alfalfa had the highest disappearance of all degradable fractions except lignin(sa). Potential disappearance (PD) fraction for ADFom, lignin(sa) and N were lower for the native legumes versus alfalfa. No differences in N proportion remaining at 24 and 48 h occurred in the native legumes despite differences in protein-bound CT proportion remaining at those same times. Of the native legumes studied, prairie acacia shows the greatest potential for contributing rumen-escape protein, suggesting it may be a candidate for further development as a pasture and rangeland renovation legume.     

Induction of kinetochore positive and negative micronuclei in V79 cells by N-methyl-N′-nitro-N-nitrosoguanidine: the protective effect of the pyridoindole antioxidant stobadine

The induction of micronuclei by N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) and their reduction by the cardioprotective synthetic antioxidant, stobadine were studied in hamster V79 cells cultured in vitro. The micronuclei derived from acentric fragments or from whole chromosomes were evaluated with the help of an immunofluorescent staining using antikinetochore antibodies from the serum of scleroderma (CREST syndrome) patients. Our results showed that MNNG (0.5 μg/ml) induced mainly kinetochore-negative micronuclei. At 6, 24 and 48 h after MNNG treatment, we measured a 2.7-, 4.3- and 7.0-fold increase, respectively, of kinetochore-negative micronuclei over the controls. The increase of kinetochore-positive micronuclei was rather low and represented at 6, 24 and 48 h, respectively 0.9-, 1.8- and 2.6-fold increases over the controls. Stobadine decreased the level of kinetochore-negative micronuclei at 6, 24 and 48 h to approximately one-half; the frequency of kinetochore-positive micronuclei was reduced only at 6 h. We suppose that the antioxidant stobadine reduces the induction of micronuclei by MNNG by scavenging of MNNG-induced highly reactive OH radicals which cause chromosomal damage.