Rizóbios são bactérias estritamente aeróbias, quimioorganotróficas, com a forma de bastonetes não formadoras de esporos, Gram-negativas, com um tamanho que varia de 0,5- 0,9 µm X 1,2-3,0 µm. Normalmente encontradas no solo, fixam nitrogênio atmosférico (N2) em simbiose com leguminosas e algumas plantas não leguminosas, induzindo a formação de nódulos nas raízes, permanecendo nestas como bacteróides fixadores de nitrogênio. No Brasil rizóbios são inoculados em lavouras de soja, pois a inoculação com bactérias fixadoras de nitrogênio supre totalmente a necessidade de utilização de adubos nitrogenados. No presente estudo foi realizada uma análise comparativa entre as espécies Bradyrhizobium japonicum (estirpe USDA 110) e Bradyrhizobium elkanii (estirpe SEMIA 587) através da aplicação da técnica de RDA (Representational Difference Analysis). RDA é uma técnica bastante útil para revelar seqüências únicas entre dois genomas ou transcritomas semelhantes. Após três ciclos de hibridizações subtrativas e amplificações dos fragmentos tester, fragmentos de aproximadamente 300 pb foram gerados. Estes fragmentos foram clonados em pUC18 e seqüênciados. Das 200 seqüências obtidas, 46 pertenceram exclusivamente à B. elkanii e 154 tiveram homologia com B. japonicum. Entre as 46 seqüências sem homologia com B. japonicum...
High levels of cyclic [beta]-1,6-1,3-glucans (e.g. 0.1 mg mg-1 of total protein) are synthesized by free-living cells as well as by bacteroids of Bradyrhizobium japonicum USDA 110 (K.J. Miller, R.S. Gore, R. Johnson, A.J. Benesi, V.N. Reinhold  J Bacteriol 172: 136-142; R.S. Gore and K.J. Miller  Plant Physiol 102: 191-194). These molecules share structural features with glucan fragments isolated from the mycelial cell wall of the soybean (Glycine max) pathogen Phytophthora megasperma. These latter glucans have been shown to be potent elicitors (at nanogram levels) of the phytoalexin glyceollin in G. max. Using the well-characterized soybean cotyledon bioassay, we now show that the cyclic [beta]-1,6-1,3-glucans of B. japonicum USDA 110 are also biologically active elicitors of glyceollin production (but at microgram levels). We further show that both classes of [beta]-glucans elicit the production of the isoflavone daidzein within soybean cotyledon wound droplets.
Rhizobium fredii USDA 206 harbors four large plasmids, one of which carries nodulation and nitrogen fixation genes. Previously isolated groups of plasmid-cured derivatives of strain USDA 206 were compared with each other to determine possible plasmid functions. Mutant strain 206CANS was isolated as a nonmucoid (Muc−) derivative of strain 206CA, a mutant that was cured of two plasmids. The Muc− phenotype of 206CANS was only expressed when the strain was grown on certain media, particularly those with polyols as carbon sources. Plasmid pRj206b of strain 206CANS was previously shown to have a higher copy number than the same plasmid in strains USDA 206 and 206CA. When this plasmid was transferred to Muc+ strains, it conferred a nonmucoid phenotype on recipient strains. The symbiotic effectiveness of the wild-type and cured strains was compared. Overall, few differences were shown, but strains 206CA and 206CANS were found to have higher nitrogenase activities than the other strains. Thus, there appeared to be a possible relationship among exopolysaccharide synthesis, plasmid copy number, and symbiotic effectiveness.
A phosphocholine-substituted beta-1,3;1,6 cyclic glucan (PCCG), an unusual cyclic oligosaccharide, has been isolated from Bradyrhizobium japonicum USDA 110 (D. B. Rolin, P. E. Pfeffer, S. F. Osman, B. S. Swergold, F. Kappler, and A. J. Benesi, Biochim. Biophys. Acta 1116:215-225, 1992). Data presented here suggest that PCCG synthesis is dependent on the carbon metabolism and that osmotic regulation of its biosynthesis parallels regulation of membrane-derived oligosaccharide biosynthesis observed in Escherichia coli (E. P. Kennedy, M. K. Rumley, H. Schulman, and L. M. G. van Golde, J. Biol. Chem. 251:4208-4213, 1976) and Agrobacterium tumefaciens (G. A. Cangelosi, G. Martinetti, and E. W. Nester, J. Bacteriol. 172:2172-2174, 1990). Growth of B. japonicum USDA 110 cells in the reference medium at relatively low osmotic pressures (LO) (65 mosmol/kg of H2O) caused a large accumulation of PCCG and unsubstituted beta-1,3;1,6 cyclic glucans (CG). Sucrose and polyethylene glycol, nonionic osmotica, reduce all growth rates and inhibit almost completely the production of PCCG at high osmotic pressures (HO) above 650 and 400 mosmol/kg of H2O), respectively. We used in vivo 13C nuclear magnetic resonance spectroscopy to identify the active osmolytes implicated in the osmoregulation process. The level of alpha...
Previously, Bradyrhizobium japonicum USDA 110 was shown to contain colony morphology variants which differed in nitrogen-fixing ability. Mannitol-utilizing derivatives L1-110 and L2-110 have been shown to be devoid of symbiotic nitrogen fixation ability, and non-mannitol-utilizing derivatives I-110 and S-110 have been shown to be efficient at nitrogen fixation. The objectives of this study were to determine the effect of media carbon sources on the symbiotic N2-fixing ability of strain USDA 110 and to compare the effectiveness of strain USDA 110 and derivative I-110. Based on acetylene reduction activity and the nitrogen content of 41-day-old soybean plants, neither derivative I-110 nor cultures of USDA 110 grown in media favoring non-mannitol-using derivatives had symbiotic nitrogen fixation that was statistically superior to that of cultures of USDA 110 grown in media favoring mannitol-using derivatives. In another experiment 200 individual nodules formed by strain USDA 110 grown in yeast extract gluconate were screened for colony morphology of occupying variant(s) and acetylene reduction activity. Nodules occupied by mannitol-using derivatives (large colony type on 0.1% yeast extract-0.05% K2HPO4-0.08% MgSO4 · 7H2O-0.02% NaCl-0.001% FeCl3 · 6H2O [pH 6.7] with 1% mannitol [YEM] plates) had a mean acetylene reduction activity equal to that of nodules occupied by non-mannitol-using derivatives (small colony type on YEM plates). A total of 20 large colonial derivatives and 10 small colonial derivatives (I-110-like) were isolated and purified by repeated culture in YEM and YEG (same as YEM except 1% gluconate instead of 1% mannitol) media...
We have isolated a colonial derivative of Bradyrhizobium japonicum USDA 110 (designated MN-110) that is both mannitol utilizing and N2 fixing. Derivative MN-110 showed growth on mannitol and glucose similar to that of non-N2-fixing, mannitol-utilizing L2-110. Derivative MN-110 showed high constitutive and induced d-mannitol dehydrogenase activity (similar to L2-110) relative to N2-fixing, non-mannitol-utilizing I-110. Hybridization to EcoRI and HindIII total DNA digests with cloned USDA 110 nif DK and nif H genes revealed similar patterns for non-N2-fixing mannitol-utilizing derivative L1-110 and derivative MN-110. Symbiotic tests with soybean cultivars Ransom and Lee indicate MN-110 to be a superior N2-fixing derivative compared with derivative I-110 and the parent strain USDA 110. However, these differences were not revealed when comparing 28-day-old soybean-B. japonicum associations but were apparent in 49-day-old associations. It was apparent from this work that mannitol utilization was not necessarily correlated to symbiotic effectiveness in B. japonicum and that gene rearrangements were not responsible for differences in N2 fixation between L1-110 or L2-110 and MN-110.
Several Rhizobium genes (designated nod genes) are involved in early steps in nodule formation. Here we present the results of DNA sequence and functional analysis of two nodD genes from the symbiotic plasmid of USDA 191, a fast-growing strain that forms nitrogen-fixing nodules on soybeans. Both genes encoded full-length nodD-related polypeptides, which were 69% homologous to each other. One of these genes, nodD1, complemented a Rhizobium trifolii nodD::Tn5 mutant for clover nodulation; the other gene, nodD2, did not. The nodD1 coding region was preceded by a conserved DNA sequence previously noted in other rhizobia, but no such sequence was found in front of nodD2. Plants inoculated with a nodD1 insertion mutant appeared to be nitrogen starved and had a greatly reduced nodule number. Plants inoculated with a nodD2 mutant had a partially nitrogen-starved appearance and normal nodule number, were slightly delayed in nodule formation, and formed nodules that contained reduced levels of nodulin-35 and had fewer bacteroids per infected plant cell. Thus, both of these genes are involved in symbiosis. USDA 191 carrying extra copies of nodD2 on a plasmid vector had an altered colony morphology that suggested inhibition of exopolysaccharide synthesis. The predicted gene products of nodD1 and nodD2 both showed homology to LysR...
The extracellular polysaccharides and lipopolysaccharides (LPSs) from two fast-growing Rhizobium japonicum strains, USDA 205 and HC205, were isolated and partially characterized. Strain HC205 is a Nod- mutant of USDA 205 which lacks the symbiotic plasmid. The extracellular polysaccharides from both strains are very similar in composition, having galactose, glucose, glucuronic acid, and acyl groups. The extracellular polysaccharides do not contain detectable levels of pyruvate. Methylation analysis shows that the extracellular polysaccharides from both strains have the same glycosyl linkages. The LPSs were purified by a modified phenol-water extraction procedure and gel filtration chromatography. The LPSs from USDA 205 and HC205 elute as broad peaks from the gel filtration column and contain 2-keto-3-deoxyoctonic acid as one of the major sugar components. Each broad 2-keto-3-deoxyoctonic acid-containing peak has a distinct shoulder on its leading edge. The shoulder and the remainder of the broad peak are separated and labeled LPSI and LPSII, respectively. Glucose (and 2-keto-3-deoxyoctonic acid) is a major sugar in the LPSI fractions. Both the LPSII fractions contain 2-keto-3-deoxyoctonic acid as the major sugar (about 20% of the mass). There are a number of quantitative differences in these LPS fractions between strain USDA 205 and HC205. Polyacrylamide gel electrophoresis shows that the LPSs are heterogeneous molecules but less heterogeneous than the LPSs from Salmonella minnesota or Rhizobium leguminosarum. The LPSI fractions from both USDA 205 and HC205 show a single lower-molecular-weight band and a higher-molecular-weight banding region which contains several bands. No bands are observed for the LPSII fractions from either USDA 205 or HC205.
DNAs from Bradyrhizobium japonicum USDA 110 derivatives that differ in nitrogen-fixing ability produced similar electrophoretic patterns with five different restriction enzymes. Our data support the hypothesis of common ancestry for these derivatives. Derivatives I-110 and L1-110 differed as much as 100-fold in acetylene reduction activity when they were tested with several soybean cultivars in both greenhouse and field experiments. While possessing nodulating ability, derivative L1-110 is deficient in symbiotic nitrogen-fixing ability, whereas derivative I-110 is symbiotically competent. Hybridization of nifDK and nifH probes from B. japonicum to Southern blots of restricted DNAs from strain USDA 110 derivatives produced similar patterns. This finding indicates similar structural gene organization for both derivative I-110 and derivative L1-110 and implies that the difference in symbiotic nitrogen fixation is probably not due to structural gene rearrangements. However, our hybridization data do not rule out the possibility of differences in expression of structural nif genes or alterations in the structure or expression of other genes required for symbiotic nitrogen fixation.
Nodulation, acetylene reduction activity, dry matter accumulation, and total nitrogen accumulation by nodulated plants growing in a nitrogen-free culture system were used to compare the symbiotic effectiveness of the fast-growing Rhizobium fredii USDA 191 with that of the slow-growing Bradyrhizobium japonicum USDA 110 in symbiosis with five soybean (Glycine max (L.) Merr.) cultivars. Measurement of the amount of nitrogen accumulated during a 20-day period of vegetative growth (28 to 48 days after transplanting) showed that USDA 110 fixed 3.7, 39.1, 4.6, and 57.3 times more N2 than did USDA 191 with cultivars Pickett 71, Harosoy 63, Lee, and Ransom as host plants, respectively. With the unimproved Peking cultivar as the host plant, USDA 191 fixed 3.3 times more N2 than did the USDA 110 during the 20-day period. The superior N2 fixation capability of USDA 110 with the four North American cultivars as hosts resulted primarily from higher nitrogenase activity per unit nodule mass (specific acetylene reduction activity) and higher nodule mass per plant. The higher N2-fixation capability of USDA 191 with the Peking cultivar as host resulted primarily from higher nodule mass per plant, which was associated with higher nodule numbers. There was significant variation in the N2-fixation capabilities of the four North American cultivar-USDA 191 symbioses. Pickett 71 and Lee cultivars fixed significantly more N2 in symbiosis with USDA 191 than did the Harosoy 63 and Ransom cultivars. This quantitative variation in N2-fixation capability suggests that the total incompatibility (effectiveness of nodulation and efficiency of N2 fixation) of host soybean plants and R. fredii strains is regulated by more than one host plant gene. These results indicate that it would not be prudent to introduce R. fredii strains into North American agricultural systems until more efficient N2-fixing symbioses between North American cultivars and these fast-growing strains can be developed. When inoculum containing equal numbers of USDA 191 and of strain USDA 110 was applied to the unimproved Peking cultivar in Perlite pot culture...
An electronic workshop was conducted on 4 November–13 December 2002 to discuss current issues and needs in animal bioinformatics. The electronic (e-mail listserver)
format was chosen to provide a relatively speedy process that is broad in scope,
cost-efficient and easily accessible to all participants. Approximately 40 panelists
with diverse species and discipline expertise communicated through the panel e-mail
listserver. The panel included scientists from academia, industry and government, in
the USA, Australia and the UK. A second ‘stakeholder’ e-mail listserver was used to
obtain input from a broad audience with general interests in animal genomics. The
objectives of the electronic workshop were: (a) to define priorities for animal genome
database development; and (b) to recommend ways in which the USDA could provide
leadership in the area of animal genome database development. E-mail messages
from panelists and stakeholders are archived at http://genome.cvm.umn.edu/bioinfo/.
Priorities defined for animal genome database development included: (a) data
repository; (b) tools for genome analysis; (c) annotation; (d) practical application of
genomic data; and (e) a biological framework for DNA sequence. A stable source of
In 2007, the USDA Animal Genomics Strategic Planning Task Force prepared a Blueprint to direct national needs for future research, education, and extension efforts in agricultural animal genomics. This plan is entitled "Blueprint for USDA Efforts in Agricultural Animal Genomics 2008–2017". The Blueprint is reviewed from the perspective of a molecular biologist working within the poultry breeding industry. The diverse species used in animal agriculture require different tools, resources and technologies for their improvement. The specific requirements for chickens are described in this report.
Over one-half of U.S. adults use dietary supplements, so federally supported research into the safety and effectiveness of these compounds is important for the health of many Americans. Data collected in the Computer Access to Research on Dietary Supplements database, which compiles federally sponsored dietary supplement-related research, are useful to scientists in determining the type of dietary supplement research that federal agencies are currently funding and where research gaps exist. This article describes the dietary supplement-related research funded by the NIH and the USDA. Between fiscal years 1999 and 2007, the number of research projects and funding for dietary supplement research more than doubled. During that period, NIH funded 6748 dietary supplement-related projects at a cost of $1.9 billion and the USDA funded 2258 projects at a cost of $347 million. The top funded dietary supplement ingredient categories were vitamins and minerals, botanicals, phytochemicals, and fatty acids. Cancer was by far the most frequent health outcome in dietary supplement research funding, nearly double the next closest health outcome category. Other health outcomes with the greatest funding were cellular and molecular mechanisms, cardiovascular health...
This paper takes a look at regulations proposed by the USDA last June pursuant to its authority under the Packers & Stockyard Act of 1921. The Packers & Stockyard act was passed shortly after the FTC Act and was meant to aid in enforcing the antitrust laws in the meatpacking sector. After ninety years without regulations, several courts of appeals recently began pushing back on the USDA’s interpretation of the Act and begin requiring additional proof beyond what the USDA felt was necessary. In response, and at the urging of Congress, the USDA proposed the rules addressed in this paper. After their proposal, industry participants and Congress voiced concern that the regulations stretched too far. Due to the substantial change proposed by these regulations, a complete review of all proposed changes is beyond the scope of this paper. I examine parts of the regulations in light of other laws and antitrust policies previously enforced. I conclude that some of the proposed regulations are nothing more than agricultural versions of laws that exist in other industries while other regulations appear unprecedented and should be interpreted narrowly.
The scope of the organic food debate has embroiled more constituents than simply consumers and producers of organic food. At each step along the way various interest groups such as small organic farmers, private organic certifiers, politicians, international community members, large agri-business lobbyists, environmental groups, consumers and general taxpayers have all added their voices to the debate. The USDA and other parties instrumental to the ongoing drafting of regulations for the National Organic Program have the formidable task of coming up with a cohesive, prudent, and enforceable regime for the organic industry. The original timetable for the implementation of organic regulations has long since been proven to be unrealistic. Now that we are over nine years into the drafting process, the time has come to finally synthesize the divergent comments into a workable set of regulations. Unfortunately, the momentum of the USDAâ€™s bureaucratic machinery has nearly slowed to a stand-still, and the once polarized constituent groups have become even further polarized and unwilling to compromise. Recognizing the current state of affairs and hoping to add a unique overview approach to the debate, the purpose of my paper is four-fold. First...
This paper discusses the relationship between three staples of American culture: the hot dog, the Food & Drug Administration (FDA) and the United States Department of Agriculture (USDA). The reader is first introduced to the hot dog and takes a fun and illustrative journey through the hot dogâ€™s storied tradition. Then, the paper addresses government regulation of hot dogs. Although hot dogs are principally regulated by the United States Department of Agriculture, FDA plays an integral role in the regulation and safety of hot dogs. Specifically, hot dogs raise many health concerns. Hot dogs contain many additives, such as sodium nitrite, and host harmful bacteria, such as Listeria monocytogenes, which can give rise to food-borne illness. Despite USDA regulation of the meat industry, FDA retains jurisdiction in the areas of food additives and food-borne illness, and FDA interacts with USDA and other agencies in order to address these health concerns.
One of the more unusual attempts by the American state to mobilize academic expertise unfolded in the late 1930s, when the United States Department of Agriculture (USDA) hired scholars in the “culture and personality” fields and philosophy to aid its efforts to promote economic, social, and cultural change in the countryside. USDA progressives also reached out to disciplinary scholars in other ways as they sought to institute a deliberative mode of planning in local communities and to remake the curricula of the land-grant colleges in support of that project. These USDA initiatives and scholars’ responses reveal that scientific knowledge was mobilized in the 1930s not just for the instrumental purpose of regulating economic behavior but also to explain and legitimate federal programs and to inform ambitious projects for cultural change. At the USDA, as at many other sites between the wars, scientific thinkers turned to the social sciences and philosophy in order to understand and then change the public mind.; History
An electronic workshop was conducted on 4 November–13 December 2002 to discuss current issues and needs in animal bioinformatics. The electronic (e-mail listserver) format was chosen to provide a relatively speedy process that is broad in scope, cost-efficient and easily accessible to all participants. Approximately 40 panelists with diverse species and discipline expertise communicated through the panel e-mail listserver. The panel included scientists from academia, industry and government, in the USA, Australia and the UK. A second ‘stakeholder’ e-mail listserver was used to obtain input from a broad audience with general interests in animal genomics. The objectives of the electronic workshop were: (a) to define priorities for animal genome database development; and (b) to recommend ways in which the USDA could provide leadership in the area of animal genome database development. E-mail messages from panelists and stakeholders are archived at http://genome.cvm.umn.edu/bioinfo/. Priorities defined for animal genome database development included: (a) data repository; (b) tools for genome analysis; (c) annotation; (d) practical application of genomic data; and (e) a biological framework for DNA sequence. A stable source of funding...
The purpose of this paper is to investigate the reasons how conflicts between the USDA and FDA create obstacles to effective public health policy exist in the United States. I will begin my investigation by briefly outlining the earlier chronology of meat regulation in the United States. When I reach the period of time in which poultry inspection became mandatory, I will engage in a more in depth historical analysis of the reasons why the system which prevails today developed as it did. This portion of the paper is based largely upon Congressional hearings, reports, and floor debate. I will then conclude by noting proposals for reform and offer my own assessment of division of food regulation between USDA and FDA.