Evaluation of recombinant invasive, non-pathogenic Eschericia coli as a vaccine vector against the intracellular pathogen, Brucella

Background  

There is no safe, effective human vaccine against brucellosis. Live attenuated Brucella strains are widely used to vaccinate animals. However these live Brucella vaccines can cause disease and are unsafe for humans. Killed Brucella or subunit vaccines are not effective in eliciting long term protection. In this study, we evaluate an approach using a live, non-pathogenic bacteria (E. coli) genetically engineered to mimic the brucellae pathway of infection and present antigens for an appropriate cytolitic T cell response.     

Synthesis of new thiophenolato hydrido iron(II) complexes and their substitution reactions with alkynes

The novel thiophenolato hydrido iron(II) complexes [cis-Fe(H)(SAr)(PMe₃)₄] (4–6) (Ar = p-BrC₆H₄ (4), p-MeOC₆H₄ (5) and o-MeC₆H₄ (6)) were prepared through the reaction of Fe(PMe₃)₄ with thiophenols ArSH (1–3). Reaction of 6 with trimethylsilylacetylene and phenylacetylene afforded bisalkynyl iron(II) complexes [Fe(PMe₃)₄(CCSiMe₃)₂] (7) and [Fe(PMe₃)₄(CCPh)₂] (9) through elimination of dihydrogen and the formation of thiophenol. The reaction of 5 with 2-methyl-3-butyn-2-ol gave [Fe(PMe₃)₄(CCCMe₂OH)₂] (10). The crystal structures of complexes 4, 7 and 10 were determined by X-ray diffraction. A mechanism for the formation of 7 is proposed.     

Re-investigation of ortho-metalated N,N-dialkylbenzylamine complexes of rare-earth metals. First structurally characterized arylates of neodymium and gadolinium Li[LnAr4]

The influence of the ether ligand in [LnCl₃(solv)_n], solv = THF, DME; n = 1–3 in reactions with ortho-lithiated dimethyl-benzylamine Li(dmba) has been studied. An improved protocol towards homoleptic tris-aryl complexes of the type [Ln(dmba)₃], Ln = Y, Er and Yb has been developed and molecular structures of these complexes have been established by X-ray crystallography. For the first time stable homoleptic lithium ate-complexes of the type Li[Ln(dmba)₄] (Ln = Gd, Nd) have been isolated and structurally characterized. The success in their synthesis strongly depends on the choice of the appropriate [LnCl₃(solv)_n] precursor, such as [GdCl₃(dme)₂], [NdCl₃(dme)], and THF-free reaction conditions. Factors influencing on possible degradation pathways of lanthanide tris-aryl complexes with dmba-type ligands are discussed.     

Detection of Single Quantum Dots in Model Systems with Sheet Illumination Microscopy

Single molecule detection and tracking provides at times the only possible method to observe the interactions of low numbers of biomolecules, inlcuding DNA, receptors and signal mediating proteins in living systems. However, most existing imaging methods do not enable both high sensitivity and non-invasive imaging of large specimens. In this study we report a new setup for selective plane illumination microscopy (SPIM), which enables fast imaging and single molecule tracking with the resolution of confocal microscopy and the optical penetration beyond 300 μm. We detect and report our instrumental figures of merit, control values of fluorescence properties of single nano crystals in comparison to both standard widefield configurations, and also values of nanocrystals in multicellular “fruiting bodies” of Dictyostelium, an excellent control as a model developmental system. In the Dictyostelium , we also report some of our first tracking of single nanocrystals with SPIM. The new SPIM setup represents a new technique, which enables fast single molecule imaging and tracking in living systems.     

Kristallstruktur des Isothiocyanato‐Komplexes [Ph3PNH2(OEt2)][Sm(NCS)4(DME)2]

Crystal Structure of the Isothiocyanato Complex [Ph₃PNH₂(OEt₂)][Sm(NCS)₄(DME)₂] Colourless single crystals of [Ph₃PNH₂(OEt₂)][Sm(NCS)₄(DME)₂] ( 1 ) have been obtained besides of Ph₃PS from the reaction of the homoleptic phosphorane iminato complex [Sm(NPPh₃)₃]₂ with carbon disulfide in THF solution, followed by recrystallisation from DME/Et₂O. According to the crystal structure analysis 1 consists of [Ph₃PNH₂]⁺ cations with the diethylether molecule forming a N–H…O hydrogen bridge, and anions [Sm(NCS)₄(DME)₂]^–. Sm³⁺ realizes coordination number eight by four nitrogen atoms of the isothiocyanato ions and by four oxygen atoms of the DME chelates. 1 : Space group P 1, Z = 4, lattice dimensions at 193 K: a = 919.0(1), b = 1965.2(2), c = 2401.3(2) pm, α = 96.748(11)°, β = 94.827(10)°, γ = 91.720(11)°, R = 0.029.     

Phosphaniminato‐Komplexe des Zirconiums: Die Kristallstrukturen von [ZrCl3(NPPh3)(HNPPh3)2] und [ZrCl2(NPPh3)2(HNPPh3)2]

Phosphoraneiminato Complexes of Zirconium: Crystal Structures of [ZrCl₃(NPPh₃)(HNPPh₃)₂] and [ZrCl₂(NPPh₃)₂(HNPPh₃)₂] The phosphoraneiminato complexes [ZrCl₃(NPPh₃)(HNPPh₃)₂] ( 1 ) and [ZrCl₂(NPPh₃)₂(HNPPh₃)₂] ( 2 ) have been obtained by reaction of [ZrCl₄(THF)₂] with [CsNPPh₃]₄ in THF solution to give colourless moisture sensitive crystals which are characterized by X‐ray structure determinations. [ZrCl₃(NPPh₃)(HNPPh₃)₂] ( 1 ): Space group P 1, Z = 2, lattice dimensions at 193 K: a = 1209.4(2); b = 1480.8(2); c = 1814.2(2) pm; α = 71.203(13)°, β = 71.216(13)°, γ = 74.401(13)°; R = 0.0476. The zirconium atom of 1 is oktahedrally coordinated by the three chlorine atoms in meridional arrangement and by the three nitrogen atoms of the (NPPh₃^–) ligand and of the two phosphane imine molecules HNPPh₃. The ZrN bond distance of the (NPPh₃^–) group (193.5 pm) corresponds with a double bond. [ZrCl₂(NPPh₃)₂(HNPPh₃)₂] ( 2 ): Space group P 1, Z = 4, lattice dimensions at 193 K: a = 1447.6(2); b = 1925.7(2), c = 2457.0(2) pm; α = 67.317(12)°, β = 87.376(12)°, γ = 87.103(13)°; R = 0.0408. The zirconium atom in 2 is octahedrally coordinated by the two chlorine atoms in trans position, and by the nitrogen atoms of the two (NPPh₃^–) groups as well as by the two HNPPh₃ molecules. The ZrN distance of the (NPPh₃^–) ligands (198.9 and 202.0 pm) suggest some π‐interaction between the zirconium and the nitrogen atoms.     

Synthesen und Kristallstrukturen von Dialkylgalliumhydriden — dimere versus trimere Formeleinheiten

Syntheses and Crystal Structures of Dialkylgallium Hydrides — Dimeric versus Trimeric Formula Units Dialkylgallium hydrides (R = Me, Et, iPr, iBu, neopentyl) were obtained on two different synthetic routes. The dimethyl and diethyl compounds were formed by the reaction of LiH with the corresponding dialkylgallium chlorides via lithium dialkyldihydridogallate intermediates, which so far have not been isolated in a pure form. On the second route, trialkylgallium compounds were treated with [GaH₃·NMe₂Et] to yield the dialkylgallium hydrides by a substituent exchange reaction. The dimethyl, diethyl and diisopropyl compounds are trimeric in solution. That trimeric structure was verified for the diisopropyl derivative by a crystal structure determination. Di(neopentyl)gallium hydride has a dimeric structure in solution and in the solid state.     

Phosphaniminate von Alkalimetallen: Die Kristallstrukturen von [KNPCy3]4, [KNPCy3]4·2OPCy3, [CsNPCy3]4·4OPCy3 und [Li4(NPPh3)(OSiMe2NPPh3)3(DME)]

The alkalimetal phosphoraneiminates [KNPCy₃]₄, ( 1 ) [KNPCy₃]₄·2OPCy₃ ( 2 ) and [CsNPCy₃]₄·4OPCy₃ ( 3 ) (Cy = cyclohexyl) which are obtainable by the reaction of pottassium amide or cesium amide with Cy₃PI₂ or Cy₃PBr₂ in liquid ammonia, as well as the lithium derivative [Li₄(NPPh₃)(OSiMe₂NPPh₃)₃(DME)] ( 4 ) have been characterized by crystal structure determinations. 4 has been formed by the insertion reaction of silicon greaze (‐OSiMe₂)n into the LiN bonds of [LiNPPh₃]₆ in DME solution (DME = 1, 2‐dimethoxyethane). 1 : Space group P&1macr;, Z = 2, lattice dimensions at 193 K: a = 1389.8(1); b = 1408.1(1); c = 2205.2(2) pm; α = 78.952(10)?; β = 81.215(10)?; γ = 66.232(8)?; R1 = 0.0418. 2 : Space group Pbcn, Z = 4, lattice constants at 193 K: a = 2943.6(2); b = 2048.2(1); c = 1893.8(1) pm; R1 = 0.0428. 3 : Space group Cmc2₁, Z = 4, lattice dimensions at 193 K: a = 2881.6(2); b = 2990.2(2); c = 1883.7(2) pm; R1 = 0.0586. 4 ·1/2DME: Space group R&3macr;c, Z = 12, lattice dimensions at 193 K: a = b = 1583.5(1); c = 11755.3(5) pm; R1 = 0.0495. All complexes have heterocubane structures. In 1‐3 they are formed by four alkali metal atoms and by the nitrogen atoms of the (μ₃‐NPCy₃^‐) groups, whereas 4 forms a "heteroleptic" Li₄NO₃ heterocubane.     

Phosphaniminato‐Cluster von Eisen. Die Kristallstrukturen von [FeCl(NPEt3)]4, [Fe(C=C–SiMe3)(NPEt3)]4 und [Fe3Cl4{NP(NMe2)3}3]

Phosphoraneiminato Cluster of Iron. The Crystal Structures of [FeCl(NPEt₃)]₄, [Fe(C=C–SiMe₃)(NPEt₃)]₄, and [Fe₃Cl₄{NP(NMe₂)₃}₃] The reaction of iron dichloride with the silylated phosphaneimine Me₃SiNPEt₃ in the presence of potassium fluoride at 165 ?C leads to the phosphoraneiminato complex [FeCl(NPEt₃)]₄ ( 1 ). Compound 1 forms black, moisture and oxygen sensitive crystals. According to the crystal structure analysis 1 has a heterocubane structure, in which the iron and the nitrogen atoms of the NPEt₃^– groups occupy the corners of a distorted cube and form Fe–N–Fe bond angles of 83.1? and N–Fe–N angles of 96.5?. This results in significantly short Fe…Fe contacts of 272.9 pm. The results of magnetic susceptibility measurements in the range of temperatures from 1.8 to 293 K and the ⁵⁷Fe‐Mössbauer spectra in the range of temperatures from 2 to 300 K are reported. Compound 1 reacts with the lithiated acetylenes LiC=C–CMe₃ and LiC=C–SiMe₃ in n‐hexane to form the iron‐organic derivatives [Fe(C=C–R)(NPEt₃)]₄ [R = CMe₃ ( 2 a ), R = SiMe₃ ( 2 b )] keeping the heterocubane structure. Compounds 2 a and 2 b form crystals which are very reactive and also black. According to the crystal structure analysis 2 b has a Fe₄N₄ heterocubane structure which is less distorted than that in 1 with bond angles Fe–N–Fe of 85.5? and N–Fe–N of 94.2?. This leads to the longer Fe…Fe contacts of 281.4 pm. With the dimethylamido derivative Me₃SiNP(NMe₂)₃ iron dichloride reacts under conditions similar to those in the synthesis of 1 to form the dark green mixed‐valenced Fe^II/Fe^III cluster [Fe₃Cl₄{NP(NMe₂)₃}₃] ( 3 ). According to the crystal structure analysis the three iron atoms in 3 are connected via one μ₃‐N atom of a NP(NMe₂)₃^– ligand, via two μ‐N atoms of the two remaining phosphoraneiminato ligands, and via one μ‐Cl atom to form an incomplete heterocubane skeleton.