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At least 235 records · Page 13Linked to original sources

PubMed2006

Uptake of oxytetracycline and its phytotoxicity to alfalfa (Medicago sativa L.).

A series of experiments were conducted in a hydroponic system to investigate the uptake of oxytetracycline (OTC) and its toxicity to alfalfa (Medicago sativa L.). OTC inhibited alfalfa shoot and root growth by up to 61% and 85%, respectively. The kinetics of OTC uptake could be well described by Michaelis-Menten equation with Vmax of 2.25 micromol g-1 fresh weight h-1, and Km of 0.036 mM. The uptake of OTC by alfalfa was strongly inhibited by the metabolic inhibitor, 2,4-DNP (2,4-dinitrophenol), at pH 3.5 and 6.0, but not by the aquaporin competitors, glycerol and Ag+. OTC uptake, however, was significantly inhibited by Hg2+, suggesting that the inhibition of influx was due to general cellular stress rather than the specific action of Hg2+ on aquaporins. Results from the present study suggested that OTC uptake into alfalfa is an energy-dependent process.

Anti-Bacterial Agents↗

PubMed2004

Characterization of an E2-type colicin and its application to treat alfalfa seeds to reduce Escherichia coli O157:H7.

Several outbreaks of Escherichia coli O157:H7 infections have been associated with contaminated alfalfa seeds. A recently isolated E. coli strain Hu194 was capable of inhibiting 22 strains of E. coli O157:H7 and this inhibition was mediated by the production of a colicin named Hu194. The objectives of this study were to test the efficacy of treating alfalfa seeds with colicin Hu194 against E. coli O157:H7 strains, and to characterize this antimicrobial protein. Significant reductions (approximately 5 log CFU ml-1) in the viable cell counts of strains 43890 and 43895 were observed after 1-day incubation with semi-crude colicin, and after 2 days for strain 3081. Strain 43890 was successfully eliminated (5 log CFU g-1) from inoculated alfalfa seeds after soaking in a colicin suspension at a concentration of 10,000 AU/g. Treatment of alfalfa seeds inoculated with strains 43895 and 3081 required 20-fold higher concentrations of colicin Hu194 to achieve as much as 3 log CFU g-1 reductions. The genes encoding the colicin Hu194 operon were located on a 6 kb plasmid, and the sequence analysis revealed that this colicin was an E-type DNAse. From the sequence data, the estimated molecular masses of colicin Hu194, its immunity protein and lysis protein were 61.3, 10.0 and 4.8 kDa, respectively. Based on DNA and protein sequence comparisons with other E-type colicin, colicin Hu194 belonged to the type E2-colicin cluster. However, cross-immunity tests between E-group colicins suggested that Hu194 colicin was divergent from the previously characterized E2 colicins.

Bacteriocin Plasmids↗

PubMed2005

Oral immunization with pBsVP6-transgenic alfalfa protects mice against rotavirus infection.

A critical factor in edible plant-derived vaccine development is adequate expression of the exogenous antigens in transgenic plants. We synthesized a codon-optimized gene (sVP6) encoding the VP6 protein of human group A rotavirus and inserted it into the alfalfa genome using agrobacterium-mediated transformation. As much as 0.28% of the total soluble protein of the pBsVP6-transgenic alfalfa was sVP6. Female BALB/c mice were gavaged weekly with 10 mg of transgenic alfalfa extract containing 24 microg of sVP6 protein and 10 microg of CpG-rich oligodeoxynucleotides as mucosal adjuvant. Immunized mice developed high titers of anti-VP6 serum IgG and mucosal IgA. Offspring of immunized dams developed less severe diarrhea after challenge with simian rotavirus SA-11, indicating that antibodies generated in the dams provided passive heterotypic protection to the pups. These results suggest that oral immunization with pBsVP6-transgenic alfalfa provides a potential means of protecting children and young animals from severe acute rotavirus-induced diarrhea.

Administration, Oral↗

PubMed2003

Isolation of Salmonella from alfalfa seed and demonstration of impaired growth of heat-injured cells in seed homogenates.

Three major foodborne outbreaks of salmonellosis in 1998 and 1999 were linked to the consumption of raw alfalfa sprouts. In this report, an improved method is described for isolation of Salmonella from alfalfa seed lots, which had been implicated in these outbreaks. From each seed lot, eight samples each containing 25 g of seed were tested for the presence of Salmonella by the US FDA Bacteriological Analytical Manual (BAM) procedure and by a modified method applying two successive pre-enrichment steps. Depending on the seed lot, one to four out of eight samples tested positive for Salmonella by the standard procedure and two to seven out of eight samples tested positive by the modified method. Thus, the use of two consecutive pre-enrichment steps led to a higher detection rate than a single pre-enrichment step. This result indirectly suggested that Salmonella cells on contaminated seeds might be injured and failed to fully resuscitate in pre-enrichment broth containing seed components during the first 24 h of incubation. Responses of heat-injured Salmonella cells grown in buffered peptone water (BPW) and in three alfalfa seed homogenates were investigated. For preparation of seed homogenates, 25 g of seeds were homogenized in 200 ml of BPW using a laboratory Stomacher and subsequently held at 37 degrees C for 24 h prior to centrifugation and filtration. While untreated cells grew at about the same rate in BPW and in seed homogenates, heat-injured cells (52 degrees C, 10 min) required approximately 0.5 to 4.0 h longer to resuscitate in seed homogenates than in BPW. This result suggests that the alfalfa seed components or fermented metabolites from native bacteria hinder the repair and growth of heat-injured cells. This study also shows that an additional pre-enrichment step increases the frequency of isolation of Salmonella from naturally contaminated seeds, possibly by alleviating the toxic effect of seed homogenates on repair or growth of injured cells.

Colony Count, Microbial↗

PubMed1997

Effects of ozone on yield, growth, and root starch concentrations of two alfalfa (Medicago sativ A L.) cultivars.

Ozone (O3) is considered to be a major air pollutant that affects the yield of several sensitive crop species. Its concentration may reach phytotoxic levels several times during the growing season in Eastern Canada. This study was initiated to evaluate the O3 effects on alfalfa, a major crop species. The objective was to compare the yield and growth parameters of the main alfalfa cultivar used in Québec, Apica, to a cultivar more tolerant to O3, Team. Effects on root starch concentrations were also examined as this parameter is an important indicator of alfalfa perennity. The results obtained have shown that the forage yield of Apica was more reduced by O3 during two growing seasons than the yield of Team. For O3 concentrations of 20 to 40 nl liter(-1), yield reductions were 14-26% for Apica and 0-20% for Team. Whereas Apica could be considered more susceptible to O3 than Team, the latter has shown contrasting responses from year to year. This fact suggests that the mechanisms involved in O3-tolerance could be modulated by environmental conditions. At low O3 levels, Apica has shown reduced root growth in terms of dry matter and length. However, contrary to the current hypothesis that O3 would affect more root than shoot growth, we were unable to show a consistent alteration of the biomass allocation between the two. Ozone seems to reduce globally the growth of the whole plants. The greater O3-tolerance of Team could partly be associated to its capacity to maintain more leaves, to delay their senescence, or to keep a larger leaf:stem ratio under increasing levels of O3. At the end of the two growing seasons, the amount of starch reserves stored below ground was shown to be reduced by the current O3 levels. This reduction was mainly associated with a decrease in root biomass under O3 stress. This result support the hypothesis that O3 may accelerate alfalfa decline under field conditions.

Journal Article↗

PubMed1997

Characterization of somatic embryogenesis-related cDNAs from alfalfa (Medicago sativa L.).

Messenger RNAs from cultures of embryogenic and non-embryogenic alfalfa (Medicago sativa L.) genotypes were used to differentially screen a cDNA library prepared from embryogenic cell masses of somatic embryo cultures to identify early-stage embryo transcripts. The three alfalfa somatic embryogenesis-specific transcripts cDNAs (ASET1, ASET2 and ASET3) identified by this screen were enriched in RNA samples from embryogenic tissues of the embryogenic genotype but were absent from petioles or mature embryos of an embryogenic genotype as well from tissue cultures of a nonembryogenic genotype. The ASET clones did not cross-hybridize and showed different patterns of expression in northerns of RNA from various fractions of alfalfa somatic embryo cultures. The ASET clones did not hybridize with the soybean embryogenesis-specific clone (Sbh1) which was shown to be expressed in embryogenic and non-embryogenic alfalfa tissue cultures. Sequencing showed ASET1 to be a partial transcript 595 nucleotides long. ASET2 was a complete transcript of 1193 nucleotides. From a comparison of the predicted open reading frame with the GenBank protein database it was concluded that ASET2 was a novel transcript. The protein predicted by the ASET2 sequence has several potential membrane-spanning domains and a potential phosphorylation site. In addition, the ASET2 cDNA had a long 5' region that contained two upstream reading frames (URFs) which could potentially code for 30 and 6 amino acid polypeptides.

Amino Acid Sequence↗

PubMed1998

Alfin1, a novel zinc-finger protein in alfalfa roots that binds to promoter elements in the salt-inducible MsPRP2 gene.

Alfin1 cDNA, obtained by differential screening of a poly(A)+ library from salt-tolerant alfalfa cells, encodes a novel protein with a Cys4 and His/Cys3 putative zinc-binding domain that suggests a possible role for this protein in transcriptional regulation. We have expressed the cDNA in Escherichia coli and show that the recombinant Alfin1 protein binds DNA in a sequence-specific manner. The DNA recognition sequence was determined from individual clones isolated after four rounds of random oligonucleotide selection in gel retardation assays, coupled with PCR amplification of the selected sequences. The consensus binding site for Alfin1 is shown to contain two to five G-rich triplets with the conserved core of GNGGTG or GTGGNG in clones showing high-efficiency binding. DNA binding of the recombinant Alfin1 was inhibited by EDTA. Alfin1 mRNA was found predominantly in alfalfa roots. Growth of salt-sensitive Medicago sativa L on 171 mM NaCl led to a slight decrease in Alfin1 mRNA, while the salt-tolerant plants showed no decrease in Alfin1 mRNA levels. Interestingly, recombinant Alfin1 binds efficiently to three fragments of the MsPRP2 promoter, each containing consensus sequences identified by the random oligonucleotide selection. Since MsPRP2 transcripts were shown to be root-specific and accumulated in alfalfa roots in a salt-inducible manner, Alfin1 may play a role in the regulated expression of MsPRP2 in alfalfa roots and contribute to salt tolerance in these plants.

Amino Acid Sequence↗

PubMed2000

Multiple cyclin-dependent kinase complexes and phosphatases control G2/M progression in alfalfa cells.

Reversible phosphorylation of proteins by kinases and phosphatases plays a key regulatory role in several eukaryotic cellular functions including the control of the division cycle. Increasing numbers of sequence and biochemical data show the involvement of cyclin-dependent kinases (CDKs) and cyclins in regulation of the cell cycle progression in higher plants. The complexity represented by different types of CDKs and cyclins in a single species such as alfalfa, indicates that multicomponent regulatory pathways control G2/M transition. A set of cdc2-related genes (cdc2Ms A, B, D and F) was expressed in G2 and M cells. Phosphorylation assays also revealed that at least three kinase complexes (Cdc2Ms A/B, D and F) were successively active in G2/M cells after synchronization. Interaction between alfalfa mitotic cyclin (Medsa;CycB2;1) and a kinase partner has been reported previously. The present yeast two-hybrid analyses showed differential interaction between defined D-type cyclins and Cdc2Ms kinases functioning in G2/M phases. Localization of Cdc2Ms F kinase to the preprophase band (PPB), the perinuclear ring in early prophase, the mitotic spindle and the phragmoplast indicated a pivotal role for this kinase in mitotic plant cells. So far limited research efforts have been devoted to the functions of phosphatases in the control of plant cell division. A homologue of dual phosphatase, cdc25, has not been cloned yet from alfalfa; however tyrosine phosphorylation was indicated in the case of Cdc2Ms A kinase and the p(13suc1)-bound kinase activity was increased by treatment of this complex with recombinant Drosophila Cdc25. The potential role of serine/threonine phosphatases can be concluded from inhibitor studies based on okadaic acid or endothall. Endothall elevated the kinase activity of p(13suc1)-bound fractions in G2-phase alfalfa cells. These biochemical data are in accordance with observed cytological abnormalities. The present overview with selected original data outlines a conclusion that emphasizes the complexity of G2/M regulatory events in flowering plants.

CDC2 Protein Kinase↗

PubMed2002

Combined effects of water activity, temperature and chemical treatments on the survival of Salmonella and Escherichia coli O157:H7 on alfalfa seeds.

AIMS: The objective of this study was to determine the combined effects of water activity (a(w)), chemical treatment and temperature on Salmonella and Escherichia coli O157:H7 inoculated onto alfalfa seeds. METHODS AND RESULTS: Alfalfa seeds inoculated with Salmonella or E. coli O157:H7 and adjusted to various a(w) values were subjected to simultaneous and separate treatments with chemicals and heat. The rate of death of both pathogens was correlated with increased a(w) (0.15-0.60) and temperature (5-37 degrees C) over a 52-week storage period. Higher seed a(w) enhanced the inactivation of pathogens on seeds heated at 50-70 degrees C for up to 24 h. Treatment of seeds with water, 1% Ca(OH)2, 1% Tween 80, 1% Ca(OH)2 plus 1% Tween 80 or 40 mg l(-1) Tsunami 200 at 23 or 55 degrees C for 2 min significantly (alpha=0.05) reduced populations of Salmonella and E. coli O157:H7. CONCLUSIONS: Overall, at the combinations of temperature and concentrations of chemicals tested, 1% Ca(OH)2 was most effective in killing Salmonella and E. coli O157:H7 without reducing seed viability. SIGNIFICANCE AND IMPACT OF THE STUDY: None of the treatments evaluated in this study, whether applied separately or in combination, eliminated Salmonella or E. coli O157:H7 on alfalfa seeds without sacrificing the viability of the seeds. It remains essential that practices to prevent the contamination of alfalfa seeds be strictly followed in order to minimize the risk of Salmonella and E. coli O157:H7 infections associated with sprouts produced from these seeds.

Calcium Hydroxide↗

PubMed2002

Combined effects of chemical, heat and ultrasound treatments to kill Salmonella and Escherichia coli O157:H7 on alfalfa seeds.

AIMS: To determine the effectiveness of combined treatments with chemicals, heat and ultrasound in killing or removing Salmonella and Escherichia coli O157:H7 on alfalfa seeds intended for sprout production. METHODS AND RESULTS: Alfalfa seeds inoculated with Salmonella or E. coli O157:H7 were treated with ultrasound (38.5-40.5 kHz) in solutions containing 1% Ca(OH)(2), 1% Tween 80, 1% Ca(OH)(2) plus 1% Tween 80, 160 microg ml(-1) Tsunami 200 and 0.5% Fit at 23 and 55 degrees C for 2 and 5 min. Highest reductions were in chemical solutions at 55 degrees C, but seed viability was also reduced compared with treatment at 23 degrees C. Inactivation of Salmonella and E. coli O157:H7 was generally enhanced by simultaneous treatments with ultrasound, chemicals and heat. CONCLUSIONS: Ultrasound treatment, in combination with chemicals and heat, had a modest enhancing effect on the effectiveness of chemicals in killing or removing pathogens on alfalfa seeds. Overall, treatment with 1% Ca(OH)(2) was most effective in killing Salmonella and E. coli O157:H7. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of 1% Ca(OH)(2) instead of 20,000 microg ml(-1) chlorine, which is currently recommended as a sanitizer for seeds intended for sprout production in the US, should be considered. Ultrasound treatment of alfalfa seeds containing Salmonella or E. coli O157:H7, in combination with chemical treatment, contributes to achieving greater reductions in populations of these pathogens, thereby reducing the risk of contamination and the presence of pathogens in sprouts produced from these seeds.

Calcium Hydroxide↗

PubMed2003

Inferences from mitochondrial DNA patterns on the domestication history of alfalfa (Medicago sativa).

The evolutionary history of a wild-cultivated complex is the outcome of different factors, among which are the domestication of the cultivated form, its geographical and demographic expansion, as well as gene flow between natural and cultivated populations. To clarify this history for alfalfa (Medicago sativa), we adopted a phylogeographical approach based on a sample of natural and cultivated populations of the M. sativa species complex. This sample was characterized for mtDNA variation through restriction fragment length polymorphisms. Twenty-two mitotypes were identified in the whole data set (155 individuals). In the wild pool from the presumed area of origin (Near East to Central Asia), the diversity was high but the absence of geographical differentiation hinders a more precise location of the centre of domestication. Within the cultivated alfalfa, the geographical structure suggests strongly the existence of at least two independent routes of dissemination of alfalfa from its centre of origin. In particular, original mitotypes detected in some regions suggest that wild populations not sampled in this study, and located outside the presumed area of domestication, may have contributed to the diversity of the cultivated pool. Finally, analysis of the mtDNA variation shows that natural populations collected in Spain constitute an endemic wild pool now introgressed partially by cultivated alfalfa.

Crops, Agricultural↗

PubMed1992

Molecular characterization and expression of an alfalfa protein with sequence similarity to mammalian ERp72, a glucose-regulated endoplasmic reticulum protein containing active site sequences of protein disulphide isomerase.

A complementary DNA clone (G1) containing sequence similarity to the mammalian lumenal endoplasmic reticulum protein ERp72 was isolated from an alfalfa (Medicago sativa L.) cDNA library by screening with a cDNA encoding human protein disulphide isomerase (PDI), which contains two thioredoxin-like active site regions which are highly conserved in ERp72. The polypeptide encoded by G1 consists of 364 amino acids, possesses a putative N-terminal secretory signal sequence and two regions, 113 amino acids apart, identical to the active sites of PDI and ERp72. G1 appears to be encoded by a small gene family in alfalfa, whose transcripts are constitutively expressed in all major organs of the plant. In alfalfa cell suspension cultures, G1 transcripts were markedly induced by treatment with tunicamycin, but not in response to calcium ionophore, heat shock or fungal elicitor. A similar expression pattern was observed for transcripts encoded by B2, a recently cloned alfalfa cDNA with strong sequence similarity to PDI. We discuss potential roles of plant proteins resembling vertebrate PDI and ERp72.

Amino Acid Sequence↗

PubMed1995

Alfalfa NADH-dependent glutamate synthase: structure of the gene and importance in symbiotic N2 fixation.

Glutamate synthase (GOGAT), a key enzyme in ammonia (NH+4) assimilation, occurs as two forms in plants: a ferredoxin-dependent form (Fd-GOGAT) and an NADH-dependent form (NADH-GOGAT). These enzymes are encoded by distinct genes as evidenced by their cDNA and deduced amino acid sequences. This paper reports the isolation and characterization of a NADH-GOGAT gene from alfalfa (Medicago sativa L.), the first GOGAT gene to be isolated from a eukaryote. RNase protection and primer extension experiments map the transcription start site of NADH-GOGAT to nearly identical positions. The transcribed region of this gene, 12,214 bp, is comprised of 22 exons separated by 21 introns. The 2.7 kbp region 5' from the translation initiation site confers nodule-specific reporter gene activity when used in a chimeric beta-glucuronidase (GUS) construct and transformed into Lotus corniculatus and Medicago sativa. Both infected and uninfected cells display GUS activity. The abundance of NADH-GOGAT transcripts increases substantially in developing nodules of plants infected with effective rhizobia. However, this increase is not observed when nodules are induced by a variety of ineffective rhizobial strains. Thus, unlike many other plant genes involved in root nodule NH+4 assimilation, high levels of NADH-GOGAT expression are strictly associated with effective nodules indicating that NADH-GOGAT plays a central role in the functioning of effective root nodules. An alfalfa Fd-GOGAT PCR product showing greater than 85% identity to maize Fd-GOGAT was isolated and used to investigate the contribution of this enzyme to NH+4 assimilation in nodules. Fd-GOGAT mRNA was abundant in leaves and cotyledons but was not detected in alfalfa root nodules. Fd-GOGAT in alfalfa does not appear to play a significant role in symbiotic N2 fixation.

Amino Acid Sequence↗

PubMed2003

Detection of Salmonella by indicator agar media and PCR as affected by alfalfa seed homogenates and native bacteria.

AIMS: To investigate and prevent the undesirable effect of native bacteria and alfalfa seed homogenates on detection of Salmonella in alfalfa seeds by indicator agar media and polymerase chain reaction (PCR). METHODS AND RESULTS: The relative sensitivity of five indicator agar media, including modified semisolid RV (MSRV), xylose-lysine-Tergitol 4 (XLT4), Hektoen enteric agar (HEA), brilliant green agar (BGA) and bismuth sulphite agar (BSA), for detection of Salmonella in the presence of a large number of native bacteria from alfalfa seeds was examined. The detection limit as measured by the ratio between the numbers of native bacteria and Salmonella was estimated to be 10(6) to 1 for MSRV and 10(3) to 1 for XLT4, HEA, BGA or BSA. Presence of alfalfa seed homogenates markedly reduced the sensitivity of Salmonella detection by PCR. The minimal number of Salmonella detectable by PCR was determined to be 1-10 and 100-1000 CFU in the absence and presence of seed homogenate, respectively. Application of anti-Salmonella immunomagnetic beads permitted detection of 2-5 CFU of heat-injured cells in 25 g of seeds within 24 h by PCR. CONCLUSIONS: The MSRV medium is more sensitive than other indicator agars for detecting a small number of motile Salmonella in samples containing a large number of native bacteria. Application of immunomagnetic beads eliminates the PCR-inhibitory activity of seed homogenates and improves the detection of Salmonella in inoculated seeds. SIGNIFICANCE AND IMPACT: The results generated from this study will aid the seed distributors, sprout growers and public health officials to identify and recall the Salmonella-contaminated seed lots to be used for sprout production.

Agar↗

PubMed2002

A simple alfalfa seedling infection model for Pseudomonas aeruginosa strains associated with cystic fibrosis shows AlgT (sigma-22) and RhlR contribute to pathogenesis.

A sensitive plant infection model was developed to identify virulence factors in nontypeable, alginate overproducing (mucoid) Pseudomonas aeruginosa strains isolated from cystic fibrosis (CF) patients with chronic pulmonary disease. Nontypeable strains with defects in lipopolysaccharide O-side chains are common to CF and often exhibit low virulence in animal models of infection. However, 1,000 such bacteria were enough to show disease symptoms in the alfalfa infection. A typical mucoid CF isolate, FRD1, and its isogenic mutants were tested for alfalfa seedling infection. Although defects in the global regulators Vfr, RpoS, PvdS, or LasR had no discernable effect on virulence, a defect in RhlR reduced the infection frequency by >50%. A defect in alginate biosynthesis resulted in plant disease with >3-fold more bacteria per plant, suggesting that alginate overproduction attenuated bacterial growth in planta. FRD1 derivatives lacking AlgT, a sigma factor required for alginate production, were reduced >50% in the frequency of infection. Thus, AlgT apparently regulates factors in FRD1, besides alginate, important for pathogenesis. In contrast, in a non-CF strain, PAO1, an algT mutation did not affect its virulence on alfalfa. Conversely, PAO1 virulence was reduced in a mucA mutant that overproduced alginate. These observations suggested that mucoid conversion in CF may be driven by a selection for organisms with attenuated virulence or growth in the lung, which promotes a chronic infection. These studies also demonstrated that the wounded alfalfa seedling infection model is a useful tool to identify factors contributing to the persistence of P. aeruginosa in CF.

Alginates↗

PubMed2001

The effect of forage quality and level of feeding on digestibility and gastrointestinal transit time of oat straw and alfalfa given to ponies and donkeys.

Four donkeys and four ponies were fed molassed dehydrated alfalfa or oat straw, either ad libitum or restricted to about 70% ad libitum intake in a Latin-square design for four periods of 21 d. Measurements of apparent digestibility and gastrointestinal transit time were made on the last 7 d of each period. When the forages were provided ad libitum, all animals ate significantly more of the alfalfa than of the oat straw. Ponies consumed significantly more of both diets per unit live weight than donkeys. Higher apparent digestibilities of dietary DM, energy and fibre fractions were seen in donkeys, at both levels of feeding, compared with the ponies. This partly compensated for the lower intakes by the donkeys when fed ad libitum. When intake of alfalfa was restricted, the apparent digestibility of DM was higher compared with the corresponding values when fed ad libitum, but the reverse was true for straw. This may be because restriction of a low-quality diet reduced selection of the more digestible parts of the forage. Donkeys and ponies consumed more energy and protein than required when fed alfalfa ad libitum. Both oat straw treatments provided insufficient protein to meet the predicted requirements of ponies and donkeys. Straw intakes ad libitum exceeded the estimated energy requirement for ponies by 34-51%, but donkey energy requirements were only just met. When the amount of straw offered was restricted, 78-90% of the estimated energy requirement for donkeys was met compared with 90-105% for the ponies.

Analysis of Variance↗

PubMed1992

Natural dietary ingredients (oats and alfalfa) induce covalent DNA modifications (I-compounds) in rat liver and kidney.

Mammalian tissue DNA has recently been found, via 32P postlabeling, to contain complex profiles of age-dependent bulky carcinogen adductlike covalent modifications, which have been termed I-compounds, referring to their apparent indigenous origin without exposure to exogenous carcinogens. I-compound patterns are highly species, sex, tissue, and diet specific. As shown here, the presence of certain plant ingredients in diet, i.e., ground oats and alfalfa meal, significantly contributed to the formation of these DNA derivatives. Six groups of weanling female Sprague-Dawley rats were fed one of the following diets for three months: a natural ingredient diet containing neither oats nor alfalfa (Wayne MRH 22/5 Rodent Blox), Wayne diet supplemented with oats or alfalfa or both, a purified semisynthetic diet (AIN-76A), and AIN diet supplemented with oats. The natural ingredient diet produced more complex patterns and higher levels of I-compounds than purified diet in both liver and kidney DNA. Supplementation of either diet with oats elicited the formation of four additional oats-specific I-compounds in liver DNA. Oats and alfalfa, individually and in combination, tended to significantly raise nonpolar and diminish polar I-compound levels. To determine whether the oats-related extra spots were derived from mycotoxin contamination, two groups of rats were fed either Wayne diet or Wayne diet containing zearalenone (0.05 mg/kg) for three weeks. Zearalenone significantly increased the uterine weight but did not induce any DNA adduct formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2004

Distribution of alfalfa weevil (Coleoptera: Curculionidae) larvae among postcutting locations.

A field study was conducted in 1996 and 1997 to determine survival and spatial patterns of alfalfa weevil, Hypera postica (Gyllenhal), larvae within and between windrows of swathed alfalfa, Medicago sativa L., forage as dry matter concentration increased. After harvest, the percentage of live weevil larvae residing in swathed forage decreased as swath dry matter percentage increased. Conversely, larval populations in stubble between windrows increased with increasing swath dry matter. Larval populations in stubble under windrowed forage increased slightly as windrowed forage dry matter increased. Applications of these results for the development of alfalfa harvest systems for improved cultural control of alfalfa weevil are discussed.

Animals↗