Assimilation of nod gene inducer 14C-naringenin and the incorporation of labelled carbon atoms into the acyl side chain of a host-specific Nod factor produced by Rhizobium leguminosarum bv. viciae

Ampicillin, first introduced in 1961, has probably become the most widely used penicillin in clinical pediatrics. STRUCTURE ACTIVITY RELATIONSHIPS All penicillins contain the 6-amino penicillanic acid moiety (Fig 1). Its structure includes a thiazolidine ring (A), a β-lactam ring (B), the source of antibacterial activity, and an acyl side chain (R), containing a variety of substitutions creating the family of semisynthetic penicillins. The only difference between ampicillin and penicillin G is the presence of an amino group in the acyl side chain (Fig 1). PHARMACOLOGY AND BACTERIOLOGY Ampicillin is a semisynthetic penicillin, active against Streptococus pneumoniae and certain Gram-negative bacteria, including most Haemophilus influenzae, Escherichia coli, and certain Proteus species. Compared to penicillin G, it has increased stability in acid solutions: a property facilitating oral administration and absorption. It penetrates into most body tissues; effective entry into CSF, however, occurs only with inflamed meninges. The serum half-life with normal renal function varies from four hours in newborns1 to 1.3 hours in adults.2 Ampicillin can cause an allergic, or nonallergic skin rash (Fig 2). ALLERGY Allergy (for the purposes of this discussion) is defined as a specific immunologic interaction, between either antigen and antibody, or antigen with a sensitized lymphocyte, resulting in a clinically deleterious effect. Implicit is a prior contact with the antigen.

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Nod Factor-Induced Expression of Leghemoglobin to Study the Mechanism of NH4NO3 Inhibition on Root Hair Deformation

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1997.10.2.215 ◽

1997 ◽

Vol 10 (2) ◽

pp. 215-220 ◽

Cited By ~ 52

Author(s):

Renze Heidstra ◽

Gerd Nilsen ◽

Francisco Martinez-Abarca ◽

Ab van Kammen ◽

Ton Bisseling

Keyword(s):

Gene Expression ◽

Root Hair ◽

Rhizobium Leguminosarum ◽

Cortical Cell ◽

Brefeldin A ◽

Marker Genes ◽

Nodule Formation ◽

Cdna Clones ◽

Nod Factor ◽

Root Hair Deformation

Nod factors secreted by Rhizobium leguminosarum bv. viciae induce root hair deformation, the formation of nodule primordia, and the expression of early nodulin genes in Vicia sativa (vetch). Root hair deformation is induced within 3 h in a small, susceptible zone (±2 mm) of the root. NH4NO3, known to be a potent blocker of nodule formation, inhibits root hair deformation, initial cortical cell divisions, and infection thread formation. To test whether NH4NO3 affects the formation of a component of the Nod factor perception-transduction system, we studied Nod factor-induced gene expression. The differential display technique was used to search for marker genes, which are induced within 1 to 3 h after Nod factor application. Surprisingly, one of the isolated cDNA clones was identified as a leghemoglobin gene (VsLb1), which is induced in vetch roots within 1 h after Nod factor application. By using the drug brefeldin A, it was then shown that VsLb1 activation does not require root hair deformation. The pVsLb1 clone was used as a marker to show that in vetch plants grown in the presence of NH4NO3 Nod factor perception and transduction leading to gene expression are unaffected.

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Conservation of noIR in the Sinorhizobium and Rhizobium Genera of the Rhizobiaceae Family

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1998.11.12.1186 ◽

1998 ◽

Vol 11 (12) ◽

pp. 1186-1195 ◽

Cited By ~ 28

Author(s):

Ernö Kiss ◽

Peter Mergaert ◽

Boglàrka Olàh ◽

Attila Kereszt ◽

Christian Staehelin ◽

...

Keyword(s):

Dna Binding ◽

Primary Structure ◽

Dna Hybridization ◽

Sinorhizobium Meliloti ◽

Rhizobium Leguminosarum ◽

Negative Regulation ◽

Regulatory Proteins ◽

Dna Binding Domain ◽

Nod Factor ◽

Homologous Sequences

In Sinorhizobium meliloti the NolR repressor displays differential negative regulation of nodulation genes and is required for optimal nodulation. Here, we demonstrate that the NolR function is not unique to S. meliloti but is also present in other species of the Rhizobiaceae family. DNA hybridization indicates the presence of nolR homologous sequences in species belonging to the Rhizobium and Sinorhizobium genera while no hybridization signal was detected in species from the Mesorhizobium, Bradyrhizo-bium, Azorhizobium, and Agrobacterium genera. We isolated the nolR gene from the Rhizobium leguminosarum bv. viciae strain TOM and showed that the TOM nolR gene acts similarly to S. meliloti nolR by repressing the expression of both the nodABCIJ and the nodD genes, resulting in decreased Nod factor production. The presence of a functional nolR gene in R. leguminosarum is correlated with an increased rate and extent of nodulation of pea. The conserved primary structure, the location of the DNA-binding domain, and the similar size of NolR proteins, compared with a family of small bacterial regulatory proteins including HlyU, SmtB, and the ArsR-type regulators, revealed that NolR belongs to this family.

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