General nearest neighbor preferences in G/C oligomers interrupted by A/T: correlation with DNA structure

The frequencies of occurrence of the 5' and 3' nearest neighbor doublets of oligonucleotides containing (G/C) and (A/T) blocks show strong trends. Specifically, the following trends are observed. Given a (G/C)n (A/T)m oligomer (where G/C)n indicates a sequence of length n composed solely of Gs and/or Cs and (A/T)m is a sequence of length m composed solely of As and/or Ts, and n = 3,2,1; m = 1,2,3) and a (G/mC)2 doublet, (G/C)n (A/T)m (G/C)2 greater than (G/C)n + 2 (A/T)m. That is the (G/C)2 doublet is preferentially located 3' of the oligomer, enclosing the (A/T)m stretch. The trends are strongest for n = 3, m = 1 and gradually weaken as the size of the (mG/C)n block decreases (with a concomitant increase of (A/T)m). (A/T)2 nearest neighbor flank preferentially encloses the (G/C)n block (to produce (A/T)2 (G/C)n (A/T)m). The (A/T)2 flank trends are weaker than the (G/C)2 flank ones. The (A/T)2 flank trends also decrease in strength as the size of the (G/C)n block decreases. The statistical significance of these trends in eukaryotes is very high. A possible correlation with DNA structural parameters, in particular groove geometry, is discussed.     

Hydride complexes of platinum(II) containing unsymmetrical di(phosphine) ligands: synthesis, characterization and evidence for pairwise addition of hydrogen based on parahydrogen induced polarization

Unsymmetrical di(phosphine) ligands (dpp)₂Rop (1a, b = bis(diphenylphosphino)-2-alkyl-3-oxapropane (alkyl = methyl and ethyl)) and (dpp)₂oCy (1c = trans-2-diphenylphosphinocyclohexyl diphenylphosphinite) and their Pt(II) dichloride complexes, PtCl₂((dpp)₂mop) (2a), PtCl₂((dpp)₂eop) (2b) and PtCl₂((dpp)₂oCy) (2c), have been synthesized and characterized by NMR spectroscopy. The crystal structures of 2b and 2c show that the geometry about the platinum centers is square planar. In 2b, the metal and di(phosphine) ligand chelate ring are in a chair conformation, whereas in 2c, the chelate ring conformation is a skewed boat. Initial reaction of sodium borohydride with 2a, b, c yields the monohydride monochloride complexes PtHCl((dpp)₂mop) (5a), PtHCl((dpp)₂eop) (5b) and PtHCl((dpp)₂oCy) (5c). At longer reaction times, fluxional dimeric species are obtained, [PtH((dpp)₂mop)]₂ (4a), [PtH((dpp)₂eop)]₂ (4b) and [PtH((dpp)₂oCy)]₂ (4c),and in the case of 4c two different isomers exist. The dihydride complexes PtH₂((dpp)₂mop) (3a), PtH₂((dpp)₂eop) (3b) and PtH₂((dpp)₂oCy) (3c), are prepared by further reaction of NaBH₄ and 2. Hydrogen cycling is facile in the dihydride complexes 3a, b, c, and oxidative addition of H₂ proceeds in a pairwise manner as determined by the observation of parahydrogen induced polarization (PHIP) in the ¹H NMR spectra. The reductive elimination of H₂ is also shown to be concerted by reaction of dihydride complexes with D₂. Crystal data: 2b (C₃₀H₃₂Cl₆OP₂Pt), monoclinic, space group P2₁/c (No. 14), a = 13.7040(1), b = 11.3430(7), c = 21.3880(9) Å, β = 97.923(9)°, V = 3292.9(2) ų and Z = 4; 2c (C₃₀H₃₀Cl₂OP₂Pt), monoclinic, space group P2₁ (No. 4), a = 11.7360(2), b = 8.4311(2), c = 14.2789(2) Å, β = 101.290(1)°, V = 1385.52(4) ų and Z = 2.     

黑沙蒿光合能量分配组分在生长季的相对变化与调控机制

为了探明典型荒漠灌木优势物种黑沙蒿(俗名油蒿, Artemisia ordosica)光合过程能量中分配对环境波动的相对变化及其长期调节机制, 该研究于2018年4-10月在宁夏盐池毛乌素沙地, 同时使用MONITORING-PAM多通道荧光监测仪和LI-6400XT便携式光合测量仪对黑沙蒿叶片的最小荧光产量(F_o)、最大荧光产量(F_m)、稳态荧光产量(F_s)、光下最大荧光产量(F_m′)、净光合速率(P_n)、暗呼吸速率(R_d)、蒸腾速率(E)和叶片气孔导度(g_s)进行现场测定, 在实验室内计算比叶面积(SLA)、单位面积氮含量(N_area)、叶绿素含量(C_Chl)和叶绿素a/b (Chl a/b), 分析黑沙蒿光合过程能量分配中固碳耗能占比(Φ_A)、光呼吸耗能占比(Φ_PR)、调节性热耗散耗能占比(Φ_NPQ)和非调节性热耗散耗能占比(Φ_NO)与环境参数和叶性状参数之间的关系以及能量分配各组分之间的相对变化。结果表明, 光化学反应组分(Φ_A、Φ_PR)和热耗散组分(Φ_NPQ、Φ_NO)之间呈负相关竞争关系, 两组分内部呈正相关协同关系, E和Φ_A、Φ_PR正相关, 和Φ_NPQ、Φ_NO负相关。在低土壤含水量(SWC)和高饱和水汽压差(VPD)环境条件下, 黑沙蒿Φ_A、Φ_PR和SLA显著降低, Φ_NPQ和Φ_NO显著增加。研究认为, 在长期干旱或高蒸散条件下, 黑沙蒿通过降低SLA等途径避免水分的过度流失, 同时将部分过剩光能由光呼吸代谢途径转移到热耗散组分进行耗散。波动环境下黑沙蒿形态性状的变异和光合过程能量分配的长期调节机制, 反映了其利用形态与生理的协同可塑性对逆境的适应。     

Expression and evolution of delta9 and delta11 desaturase genes in the moth Spodoptera littoralis

Desaturation of fatty acids is a key reaction in the biosynthesis of moth sex pheromones. The main component of Spodoptera littoralis sex pheromone blend is produced by the action of Δ¹¹ and Δ⁹ desaturases. In this article, we report on the cloning of four desaturase-like genes in this species: one from the fat body (Sls-FL1) and three (Sls-FL2, Sls-FL3 and Sls-FL4) from the pheromone gland. By means of a computational/phylogenetic method, as well as functional assays, the desaturase gene products have been characterized. The fat body gene expressed a Δ⁹ desaturase that produced (Z)-9-hexadecenoic and (Z)-9-octadecenoic acids in a (1:4.5) ratio, whereas the pheromone gland Sls-FL2 expressed a Δ⁹ desaturase that produced (Z)-9-hexadecenoic and (Z)-9-octadecenoic acids in a (1.5:1) ratio. Although both Δ⁹ desaturases produced (Z)-9-tetradecenoic acid from myristic acid, transformed yeast grown in the presence of a mixture of myristic and (E)-11-tetradecenoic acids produced (Z,E)-9,11-tetradecadienoic acid, but not (Z)-9-tetradecenoic acid. The Sls-FL3 gene expressed a protein that produced a mixture of (E)-11-tetradecenoic, (Z)-11-tetradecenoic, (Z)-11-hexadecenoic and (Z)-11-octadecenoic acids in a 5:4:60:31 ratio. Despite having all the characteristics of a desaturase gene, no function could be found for Sls-FL4.     

Mitochondrial reactive oxygen production is dependent on the aromatic hydrocarbon receptor

2,3,7,8-Tetrachlorodibenzo-p-dioxin (dioxin; TCDD) is a pervasive environmental contaminant that induces hepatic and extrahepatic oxidative stress. We have previously shown that dioxin increases mitochondrial respiration-dependent reactive oxygen production. In the present study we examined the dependence of mitochondrial reactive oxygen production on the aromatic hydrocarbon receptor (AHR), cytochrome P450 1A1 (CYP1A1), and cytochrome P450 1A2 (CYP1A2), proteins believed to be important in dioxin-induced liver toxicity. Congenic Ahr(-/-), Cyp1a1(-/-) and Cyp1a2(-/-) knockout mice, and C57BL/6J inbred mice as their Ahr/Cyp1a1/Cyp1a2(+/+) wild-type (wt) counterparts, were injected intraperitoneally with dioxin (15 microg/kg body weight) or corn-oil vehicle on 3 consecutive days. Liver mitochondria were examined 1 week following the first treatment. The level of mitochondrial H(2)O(2) production in vehicle-treated Ahr(-/-) mice was one fifth that found in vehicle-treated wt mice. Whereas dioxin caused a rise in succinate-stimulated mitochondrial H(2)O(2) production in the wt, Cyp1a1(-/-), and Cyp1a2(-/-) mice, this increase did not occur with the Ahr(-/-) knockout. The lack of H(2)O(2) production in Ahr(-/-) mice was not due to low levels of Mn(2+)-superoxide dismutase (SOD2) as shown by Western immunoblot analysis, nor was it due to high levels of mitochondrial glutathione peroxidase (GPX1) activity. Dioxin decreased mitochondrial aconitase (an enzyme inactivated by superoxide) by 44% in wt mice, by 26% in Cyp1a2(-/-) mice, and by 24% in Cyp1a1(-/-) mice; no change was observed in Ahr(-/-) mice. Dioxin treatment increased mitochondrial glutathione levels in the wt, Cyp1a1(-/-), and Cyp1a2(-/-) mice, but not in Ahr(-/-) mice. These results suggest that both constitutive and dioxin-induced mitochondrial reactive oxygen production is associated with a function of the AHR, and these effects are independent of either CYP1A1 or CYP1A2.     

Nitrogen atom transfer and redox chemistry of terpyridyl phosphoraniminato complexes of osmium (IV)

Rapid reactions occur between [Os^VI(tpy)(Cl)₂(N)]X (X = PF₆⁻, Cl⁻, tpy = 2,2′:6′,2″-terpyridine) and aryl or alkyl phosphi nes (PPh₃, PPh₂Me, PPhMe₂, PMe₃ and PEt₃) in CH₂Cl₂ or CH₃CN to give [Os^IV(tpy)(Cl)₂(NPPh₃)]⁺ and its analogs. The reaction between trans-[Os^VI(tpy)(Cl)₂(N)]⁺ and PPh₃ in CH₃CN occurs with a 1:1 stoichiometry and a rate law first order in both PPh₃ and Os^VI with k(CH₃CN, 25°C) = 1.36 ± 0.08 × 10⁴ M⁻ s⁻¹. The products are best formulated as paramagnetic d⁴ phosphoraniminato complexes of Os^IV based on a room temperature magnetic moment of 1.8 μ_B for trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆), contact shifted ¹H NMR spectra and UV-Vis and near-IR spectra. In the crystal structures of trans-[Os^IV(tpy)(Cl)₂( NPPh₃)](PF₆)·CH₃CN (monoclinic, P2₁/n with a = 13.384(5) Å, b = 15.222(7) Å, c = 17.717(6) Å, β = 103.10(3)°, V = 3516(2) ų, Z = 4, R_w = 3.40, R_w = 3.50) and cis-[Os^IV(tpy)(Cl)₂(NPPh₂Me)]-(PF₆)·CH₃CN (monoclinic, P2₁/c, with a = 10.6348(2) Å, b = 15.146(9) ÅA, c = 20.876(6) Å, β = 97.47(1)°, V = 3334(2) ų, Z = 4, R = 4.00, R_w = 4.90), the long Os-N(P) bond lengths (2.093(5) and 2.061(6) Å), acute Os-N-P angles (132.4(3) and 132.2(4)°), and absence of a significant structural trans effect rule out significant Os-N multiple bonding. From cyclic voltammetric measurements, chemically reversible Os^V/IV and Os^IV/III couples occur for trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆) in CH₃CN at +0.92 V (Os^V/IV) and −0.27 V (Os^IV/III) versus SSCE. Chemical or electrochemical reduction of trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆) gives isolable trans-Os^III(tpy)(Cl)₂(NPPh₃). One-electron oxidation to Os^V followed by intermolecular disproportionation and PPh₃ group transfer gives [Os^VI(tpy)Cl₂(N)]⁺, [OS^III(tpy)(Cl)₂(CH₃CN)]⁺ and [Ph₃=N=PPh₃]⁺ (PPN⁺). trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆) undergoes reaction with a second phosphine under reflux to give PPN⁺ derivatives and Os^II(tpy)(Cl)₂(CH₃CN) in CH₃CN or Os^II(tpy)(Cl)₂(PR₃) in CH₂Cl₂. This demonstrates that the Os^VI nitrido complex can undergo a net four-electron change by a combination of atom and group transfers.     

Possible association of BLM in decreasing DNA double strand breaks during DNA replication

Bloom's syndrome (BS) is a rare genetic disorder and the cells from BS patients show genomic instability and an increased level of sister chromatid exchange (SCE). We generated BLM(-/-) and BLM(-/-)/RAD54(-/-) DT40 cells from the chicken B-lymphocyte line DT40. The BLM(-/-) DT40 cells showed higher sensitivity to methyl methanesulfonate and elevated levels of SCE as expected. The targeted integration frequency was also increased remarkably in BLM(-/-) cells. The SCE frequency increase in BLM(-/-) cells was considerably reduced and the enhanced targeted integration observed in BLM(-/-) cells was almost completely abolished in BLM(-/-)/RAD54(-/-) cells, indicating that a large portion of the SCE in BLM(-/-) cells occurs via homologous recombination, and homologous recombination events increase with the defect of BLM function. The BLM(-/-)/RAD54(-/-) cells showed a slow growth phenotype and an increased incidence of chromosome-type breaks/gaps while each single mutant showed relatively small numbers of chromosome-type breaks/gaps.     

The sex-specific impact of systolic hypertension and systolic blood pressure on arterial-ventricular coupling at rest and during exercise

In healthy subjects the arterial system and the left ventricle (LV) are tightly coupled at rest to optimize cardiac performance. Systolic hypertension (SH) is a major risk factor for heart failure and is associated with structural and functional alterations in the arteries and the LV. The effects of SH and resting systolic blood pressure (SBP) on arterial-ventricular coupling (E(a)I/E(LV)I) at rest, at peak exercise, and during recovery are not well described. We noninvasively characterized E(a)I/E(LV)I as end-systolic volume index/stroke volume index in subjects who were normotensive (NT, n = 203) or had SH (brachial SBP > or =140 mmHg, n = 79). Cardiac volumes were measured at rest and throughout exhaustive upright cycle exercise with gated blood pool scans. E(a)I/E(LV)I reserve was calculated by subtracting peak from resting E(a)I/E(LV)I. At rest, E(a)I/E(LV)I did not differ between SH and NT men but was 23% (P = 0.001) lower in SH vs. NT women. E(a)I/E(LV)I did not differ between SH and NT men or women at peak exercise or during recovery. Nevertheless, E(a)I/E(LV)I reserve was 61% (P < 0.001) lower in SH vs. NT women. Similarly, resting SBP (as a continuous variable) was not associated with E(a)I/E(LV)I in men (beta = -0.12, P = 0.17) but was inversely associated with E(a)I/E(LV)I in women (beta = -0.47, P < 0.001). SH and a higher resting brachial SBP are associated with a lower E(a)I/E(LV)I at rest in women but not in men, and SH women have an attenuated E(a)I/E(LV)I reserve. Whether a smaller E(a)I/E(LV)I reserve leads to functional limitations warrants further examination.     

The preparation and properties of the membranal DPNH dehydrogenase from Escherichia coli

1. The membrane bound DPNH oxidase of Escherichia coli can reduce the artificial electron acceptors: ferricyanide, dichlorophenolindophenol (DCIP) and menadione. All three are reduced by the flavoprotein of DPNH oxidase, but at different sites of the enzyme.

2. Freeze-drying of the bacterial membranes causes a selective detachment of DPNH dehydrogenase (DPNH: (acceptor) oxidoreductase, EC 1.6.99.3) from the membranes. This solubilization is accompanied by a decrease of K_m(K₃Fe(CN)₆) from 2.0 to 0.25 mM, while no change is detected in K_m(DPNH). This enzyme is not the DPNH diaphorase found in the bacteria.

3. DPNH dehydrogenase of E. coli is a metalloflavoprotein, containing non-heme iron, labile sulfide, FMN and FAD.

4. Reduction of the enzyme with DPNH in the absence of electron acceptor (ferricyanide or DCIP) causes a rapid and irreversible change to a less active state, Form II. Form II is characterized by a higher K_m(DPNH) and slower v_max., while the K_m(K₃Fe(CN)₆) remains unchanged.

5. The transformation of the enzyme to Form II is accompanied by the reduction of the non-heme iron component. The role of non-heme iron in the enzymic reaction is discussed.     

Effect of mutations affecting coat color on the blood lymphocyte structure in the American mink (Mustela vison Schreber, 1777)

American minks with different genotypes containing the Aleutian coat color allele in the homozygous state, including the single recessive Aleutian (a/a); double recessive sapphire (a/a p/p) and lavender (m/m a/a); triple recessive violet (m/m a/a p/p); and dominant-recessive cross sapphire (S/+ a/a p/p), sapphire leopard (S(K)/+ a/a p/p), and shadow sapphire (S(H)/+ a/a p/p) minks, as well as American minks without the Aleutian allele, including the standard (+/+); single recessive silver-blue (p/p) and hedlund-white (h/h); double recessive pearl (k/k p/p), Finnish topaz (t(S)/t(S) b/b); incompletely dominant royal silver (S(R)/+), standard leopard (S(K)/+), and black crystal (C(R)/+); and dominant-recessive snowy topaz (C(R)/+ t(S)/t(S) b/b) and Kujtezhy-spotted (S(K)/+ b/b) minks have been studied. Homozygosity for the a allele has been found to disturb the subcellular structure of leukocyte, namely the formation of abnormally large granules.     

Sensitization of mice with wild-type and cold-adapted influenza virus variants: immune response to two H1N1 and H3N2 viruses

Two A strain influenza viruses, A/Hong Kong/123/77 (A/HK/123/77) (H1N1) and A/Queensland/6/72 (A/Qld/6/72) (H3N2), and the two cold-adapted reassortants which possess the surface antigens of these strains (CR35 and CR6, respectively) were tested for their ability both to induce primary cytotoxic T-cell (Tc cell) responses in mice and to sensitize mice for a second Tc cell response when challenged with a distantly related A strain virus, A/Shearwater/72 (H6N5). After intranasal inoculation, A/Qld/6/72 replicated to higher titers in the lung (1 to 2 log10 50% egg infective doses) than did A/HK/123/77 or either of the reassortants. A/Qld/6/72 induced higher Tc cell responses in the lung than did CR6, and both were more effective than either A/HK/123/77 or CR35 in this respect. When similar doses (10 or 10(3) hemagglutinin units) of each virus were injected intravenously into mice and the spleens were tested for Tc cell activity 6 days later, both A/Qld/6/72 and CR6 were ca. 100-fold better at inducing a primary Tc cell response than A/HK/123/77 or CR35. In contrast, the H1N1 and H3N2 viruses gave rather similar anti-hemagglutinin antibody titers (after intravenous injection) and delayed-type hypersensitivity reactions (after subcutaneous injection). If mice were primed with a low dose of these viruses (10(4) 50% egg infective doses intranasally), A/Qld/6/72 and CR6 were more effective than A/HK/123/77 or CR35 at sensitizing for a secondary Tc cell response when challenged with A/Shearwater/72, but if larger doses were given either intranasally (10(6) 50% egg infective doses) or intravenously (10 to 10(3) hemagglutinin units), all viruses sensitized the mice equally well, despite the fact the A/Shearwater/72 gives a poor primary Tc cell response in mice. Thus, the viral glycoprotein antigens can be important in determining the immunogenicity of the virus and, particularly, the class I antigen-restricted Tc cell response of the host.     

Acute impact of apheresis on oxidized phospholipids in patients with familial hypercholesterolemia

We measured oxidized phospholipids (OxPL), lipoprotein (a) [Lp(a)], and lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) pre- and postapheresis in 18 patients with familial hypercholesterolemia (FH) and with low(～10 mg/dl; range 10-11 mg/dl), intermediate (～50 mg/dl; range 30-61 mg/dl), or high (>100 mg/dl; range 78-128 mg/dl) Lp(a) levels. By using enzymatic and immunoassays, the content of OxPL and Lp-PLA(2) mass and activity were quantitated in lipoprotein density fractions plated in microtiter wells, as well as directly on apoB-100, Lp(a), and apoA-I immunocaptured within each fraction (i.e., OxPL/apoB and Lp-PLA(2)/apoB). In whole fractions, OxPL was primarily detected in the Lp(a)-containing fractions, whereas Lp-PLA(2) was primarily detected in the small, dense LDL and light Lp(a) range. In lipoprotein capture assays, OxPL/apoB and OxPL/apo(a) increased proportionally with increasing Lp(a) levels. Lp-PLA(2)/apoB and Lp-PLA(2)/apoA-I levels were highest in the low Lp(a) group but decreased proportionally with increasing Lp(a) levels. Lp-PLA(2)/apo(a) was lowest in patients with low Lp(a) levels and increased proportionally with increasing Lp(a) levels. Apheresis significantly reduced levels of OxPL and Lp-PLA(2) on apoB and Lp(a) (50-75%), particularly in patients with intermediate and high Lp(a) levels. In contrast, apheresis increased Lp-PLA(2)-specific activity (activity/mass ratio) in buoyant LDL fractions. The impact of apheresis on Lp(a), OxPL, and Lp-PLA(2) provides insights into its therapeutic benefits beyond lowering apoB-containing lipoproteins.     

AT1a receptor signaling is required for basal and water deprivation-induced urine concentration in AT1a receptor-deficient mice

It is well recognized that ANG II interacts with arginine vasopressin (AVP) to regulate water reabsorption and urine concentration in the kidney. The present study used ANG II type 1a (AT(1a)) receptor-deficient (Agtr1a(-/-)) mice to test the hypothesis that AT(1a) receptor signaling is required for basal and water deprivation-induced urine concentration in the renal medulla. Eight groups of wild-type (WT) and Agtr1a(-/-) mice were treated with or without 24-h water deprivation and 1-desamino-8-d-AVP (DDAVP; 100 ng/h ip) for 2 wk or with losartan (10 mg/kg ip) during water deprivation. Under basal conditions, Agtr1a(-/-) mice had lower systolic blood pressure (P < 0.01), greater than threefold higher 24-h urine excretion (WT mice: 1.3 ± 0.1 ml vs. Agtr1a(-/-) mice: 5.9 ± 0.7 ml, P < 0.01), and markedly decreased urine osmolality (WT mice: 1,834 ± 86 mosM/kg vs. Agtr1a(-/-) mice: 843 ± 170 mosM/kg, P < 0.01), without significant changes in 24-h urinary Na(+) excretion. These responses in Agtr1a(-/-) mice were associated with lower basal plasma AVP (WT mice: 105 ± 8 pg/ml vs. Agtr1a(-/-) mice: 67 ± 6 pg/ml, P < 0.01) and decreases in total lysate and membrane aquaporin-2 (AQP2; 48.6 ± 7% of WT mice, P < 0.001) and adenylyl cyclase isoform III (55.6 ± 8% of WT mice, P < 0.01) proteins. Although 24-h water deprivation increased plasma AVP to the same levels in both strains, 24-h urine excretion was still higher, whereas urine osmolality remained lower, in Agtr1a(-/-) mice (P < 0.01). Water deprivation increased total lysate AQP2 proteins in the inner medulla but had no effect on adenylyl cyclase III, phosphorylated MAPK ERK1/2, and membrane AQP2 proteins in Agtr1a(-/-) mice. Furthermore, infusion of DDAVP for 2 wk was unable to correct the urine-concentrating defects in Agtr1a(-/-) mice. These results demonstrate that AT(1a) receptor-mediated ANG II signaling is required to maintain tonic AVP release and regulate V(2) receptor-mediated responses to water deprivation in the inner medulla.     

Strain-dependent differences in bone development, myeloid hyperplasia, morbidity and mortality in ptpn2-deficient mice

Single nucleotide polymorphisms in the gene encoding the protein tyrosine phosphatase TCPTP (encoded by PTPN2) have been linked with the development of autoimmunity. Here we have used Cre/LoxP recombination to generate Ptpn2(ex2-/ex2-) mice with a global deficiency in TCPTP on a C57BL/6 background and compared the phenotype of these mice to Ptpn2(-/-) mice (BALB/c-129SJ) generated previously by homologous recombination and backcrossed onto the BALB/c background. Ptpn2(ex2-/ex2-) mice exhibited growth retardation and a median survival of 32 days, as compared to 21 days for Ptpn2(-/-) (BALB/c) mice, but the overt signs of morbidity (hunched posture, piloerection, decreased mobility and diarrhoea) evident in Ptpn2(-/-) (BALB/c) mice were not detected in Ptpn2(ex2-/ex2-) mice. At 14 days of age, bone development was delayed in Ptpn2(-/-) (BALB/c) mice. This was associated with increased trabecular bone mass and decreased bone remodeling, a phenotype that was not evident in Ptpn2(ex2-/ex2-) mice. Ptpn2(ex2-/ex2-) mice had defects in erythropoiesis and B cell development as evident in Ptpn2(-/-) (BALB/c) mice, but not splenomegaly and did not exhibit an accumulation of myeloid cells in the spleen as seen in Ptpn2(-/-) (BALB/c) mice. Moreover, thymic atrophy, another feature of Ptpn2(-/-) (BALB/c) mice, was delayed in Ptpn2(ex2-/ex2-) mice and preceded by an increase in thymocyte positive selection and a concomitant increase in lymph node T cells. Backcrossing Ptpn2(-/-) (BALB/c) mice onto the C57BL/6 background largely recapitulated the phenotype of Ptpn2(ex2-/ex2-) mice. Taken together these results reaffirm TCPTP's important role in lymphocyte development and indicate that the effects on morbidity, mortality, bone development and the myeloid compartment are strain-dependent.     

C/EBPbeta phosphorylation by RSK creates a functional XEXD caspase inhibitory box critical for cell survival.

Upon activation by liver injury, hepatic stellate cells produce excessive fibrous tissue leading to cirrhosis. The hepatotoxin CCl(4) induced activation of RSK, phosphorylation of C/EBPbeta on Thr(217), and proliferation of stellate cells in normal mice, but caused apoptosis of these cells in C/EBPbeta-/- or C/EBPbeta-Ala(217) (a dominant-negative nonphosphorylatable mutant) transgenic mice. Both C/EBPbeta-PThr(217) and the phosphorylation mimic C/EBPbeta-Glu(217), but not C/EBPbeta-Ala(217), were associated with procaspases 1 and 8 in vivo and in vitro and inhibited their activation. Our data suggest that C/EBPbeta phosphorylation on Thr(217) creates a functional XEXD caspase substrate/inhibitor box (K-Phospho-T(217)VD) that is mimicked by C/EBPbeta-Glu(217) (KE(217)VD). C/EBPbeta-/- and C/EBPbeta-Ala(217) stellate cells were rescued from apoptosis by the cell permeant KE(217)VD tetrapeptide or C/EBPbeta-Glu(217).     

Eight-coordinate chelate complexes of zirconium(IV) and niobium(IV): X-ray diffractometric and EPR investigations

The N,N-diethylcarbamato derivative of zirconium(IV), Zr(O₂CNEt₂)₄ has been studied by X-ray crystallography. Crystal data: C₂₀H₄₀Na₄O₈Zr, monoclinic, space group C2/c, a = 14.057(1), b = 12.168(1), c = 16.746(2) Å, β = 108.071(4)°, Z = 4, D_c = 1.356, F(000) = 1168, T = 213 K. The compound is isotypic with the corresponding niobium(IV) derivative with a dodecahedral coordination at the zirconium atom. By reaction of NbCl₄(THF)₂ with Tl(hfacac), the hexafluoroacetylacetonato derivative of niobium (IV), Nb(hfacac)₄, has been prepared and structurally characterized. The compound crystallizes in the orthorhombic space group Pna2₁ with the following cell constants: a = 10.399(4), b = 15.852(9), c = 119.073(1) Å. It is not isotypic with the corresponding zirconium(IV) derivative, Zr(hfacac)₄. Crystal data: C₂₀H₄F₂₄O₈Zr, monoclinic, space group P2₁/n, a = 11.974(4), b = 20.451(6), c = 13.140(3) Å, β = 104.487(11)°, Z = 4, D_c = 1.960, F(000) = 1776, T = 223 K. Although in both compounds the central metal atom shows a square antiprismatic coordination, the coordination mode of the ligands is different and slight deviations from the D₄(llll) and C₂(llss) ideal geometries have been observed in the case of niobium and zirconium, respectively. An EPR study has been performed on the Nb(IV) derivatives as diluted solid solutions in frozen organic solvents or in the diamagnetic matrix of the corresponding zirconium(IV) compound. The EPR spectra have confirmed the presence of non-interacting paramagnets in the solid solutions and, in the case of Nb(O₂CNEt₂)₄, the point symmetry of the paramagnetic centre has been found to be in agreement with the results of the X-ray investigation. An EPR spectrum of rhombic symmetry has been observed for the hexafluoroacetylacetonato derivative of Nb(IV) when diluted in frozen THF solution or in Zr(hfacac)₄.     

Estrogen receptor regulation of pulmonary alveolar dimensions: alveolar sexual dimorphism in mice

Female rats and mice have smaller and, per body mass (BM), more alveoli and alveolar surface area (Sa) than males of their respective species. This sexual dimorphism becomes apparent about the time of sexual maturity. It is prevented in rats (not tested in mice) by ovariectomy at age 3 wk. In female mice, estrogen receptor (ER)-alpha and ER-beta are required for formation of alveoli of appropriate size and number. We now report the average volume of an alveolus (va) and the number of alveoli per body mass (Na/BM) were not statistically different between ER-alpha(-/-) and wild type (wt) males. However, the combination of a larger value for va and a smaller value for Na/BM, though neither parameter achieved a statistically significant intergroup difference, resulted in a statistically significant lower Sa/BM in ER-alpha(-/-) males compared with wt males. In ER-beta(-/-) males, va was bigger and Na/BM and Sa/BM were lower compared with wt males. Wt males had larger alveoli and lower Na/BM and Sa/BM than wt females. The wt sexual dimorphism of va, Na/BM, and Sa/BM was absent in ER-alpha(-/-) mice. Alveolar size did not differ between ER-beta(-/-) females and males but Na/BM and Sa/BM were greater in ER-beta(-/-) females than in ER-beta(-/-) males. The results in male mice, with prior findings in female mice, 1) demonstrate estrogen receptors have a smaller effect on alveolar dimensions in male than female mice, 2) show ER-alpha and ER-beta are required for the sexual dimorphism of alveolar size, and 3) show ER-alpha is needed for the sexual dimorphism of body mass-specific alveolar number and surface area.     

Comparison of combinations of diluents and media for enumerating Zygosaccharomyces rouxii in intermediate water activity foods

Combinations of five diluents (0.1% peptone, 40 and 50% glucose, and 18 and 26% glycerol) and three enumeration media (tryptone glucose yeast extract, dichloran 18% glycerol and malt extract yeast extract 50% glucose (MY50G) agars) were evaluated for recovering a xerotolerant yeast, Zygosaccharomyces rouxii , from foods with intermediate water activity ( a _w). Combinations of 40% ( a _w, 0.936) or 50% ( a _w 0.898) glucose diluent and MY50G agar ( a _w 0.890) were superior in recovering highest populations. The type of solute in the diluent, as well as a reduced a _w, influences efficiency of recovering viable cells.     

Proliferation kinetics of plasma cells and of normal haemopoietic cells in multiple myeloma

Abstract. DNA synthesis time ( T _s) and ³H thymidine (TdR) labelling index (LI) of bone marrow (BM) myelomatous plasma cells (PC) and of the residual haemopoietic cell population (RHCP) were measured by in vitro quantitative ¹⁴C-TdR autoradiography in five patients with multiple myeloma (MM) in different phases of disease (three at presentation and two at relapse) and in one patient with solitary extra-osseous myeloma. One other patient with plasma cell leukaemia (PCL) was studied during an initial relapse phase and later during the leukaemic terminal phase. PC T _s was 18.8 ± 3.7 (from 13.3 to 25.0) hr and PC LI was 2.5 ± 1.8%; (from 1.0 to 6.3%). In the case of PCL, circulating PC had a T _s of 14.4 hr and a LI of 3.1. From these experimental measurements, the fractional turnover rate (FTR—percentage of cells produced per unit time) and the potential doubling time ( T _d) of BMPC were calculated assuming that all BMPC were in a steady-state at the time of the study. BMPC FTR was 3.53 ± 2.3% cells per day (from 1.2 to 6.72) and BMPC T _d was 46.8 ± 27.5 days (from 15.0 to 75.4). Comparison with results obtained in BM blasts of children with acute lymphoblastic leukaemia (ALL) indicated that BMPC had a lower proliferative activity ( P < 0.001), although BMPC T _s was not significantly different. In two patients a tumour doubling time of 6 and 13 months was determined by clinical follow up. Comparison of this parameter with T _d showed a cell loss factor of more than 90% in both patients.
Kinetic data relative to RHCP showed slight variations with respect to those found in normal subjects, with a general tendency towards a prolongation of T _s and a reduction of LI.