Community Structure,Geochemical Characteristics and Mineralogy of a Hypersaline Microbial Mat,Cabo Rojo,PR

Seasonal variations in precipitation changed the community composition and microbial activity in a hypersaline, tropical microbial mat, in Cabo Rojo, PR. Using a combination of dissection, light, and transmission electron microscopy, terminal restriction fragment length polymorphism (T-RFLP), in situ microelectrode studies, and ³⁵ S isotope incubations, we documented the major differences between wet and dry seasons. During the wet season (precipitation 177 mm), cyanobacterial (green layer) and anoxyphototrophic (pink layer) communities, as well as the black FeS layer were well-developed, and T-RFLP patterns indicated a diverse community. The rate of oxygenic photosynthesis was 49 μ M min ^{? 1} . Aerobic respiration was 29 μ M min ^{? 1} , and sulfate reduction was 264 nmol cm ^{? 3} h ^{? 1} . During the dry season (precipitation 51 mm), cyanobacteria and anoxyphototrophs were less diverse and abundant, and T-RFLP patterns were less complex. The O ₂ production rate was reduced to 9 μ M min ^{? 1} , as was O ₂ consumption (7 μ M min ^{? 1} ) and sulfate reduction (26 nmol cm ^{? 3} h ^{? 1} ). Aragonite, calcite, halite, and quartz were the predominant minerals. Seasonal differences were found in the green and pink layers for both halite and quartz. Gypsum was not observed, likely due to a sample handling artifact. The fluctuations in community composition and metabolic activity, principally reflected in fluctuations in binding and trapping potential of the uppermost mat community, might be responsible for the observed differences in mineralogy.     

Synthesis and Hybridization Properties of Oligonucleotides Containing (2 S ,3 R )-9-(2,3,4-Trihydroxybutyl)Adenine

The synthesis and properties of oligonucleotides (ONs) containing 9-(2,3,4-trihydroxybutyl)adenine, A ^C2 and A ^C3, are described. The ON containing A ^C2 involves the 3′ → 4′ and 3′ → 5′ phosphodiester linkages in the strand, whereas that containing A ^C3 possesses the 3′ → 4′ and 2′ → 5′ phosphodiester linkages. It was found that incorporation of the analogs, A ^C2 or A ^C3, into ONs significantly reduces the thermal and thermodynamic stabilities of the ON/DNA duplexes, but does not largely decrease the thermal and thermodynamic stabilities of the ON/RNA duplexes as compared with the case of the ON/DNA duplexes. It was revealed that the base recognition ability of A ^C2 is greater than that of A ^C3 in the ON/RNA duplexes.     

Evaluation of novel <Superscript>99m</Superscript>Tc(I)-labeled homobivalent α-melanocyte-stimulating hormone analogs for melanocortin-1 receptor targeting

Abstract  

Aiming to apply the multivalency concept to melanoma imaging, we have assessed the in vivo melanocortin type 1 receptor (MC1R)-targeting properties of ^99mTc(I)-labeled homobivalent peptide conjugates which contain copies of the α-melanocyte-stimulating hormone (α-MSH) analog [Ac-Nle⁴, Asp⁵, d-Phe⁷, Lys¹¹]α-MSH_4–11 separated by linkers of different length (L ² nine atoms and L ³ 14 atoms). The MC1R-binding affinity of L ² and L ³ is significantly higher than that of the monovalent conjugate L ¹ . Metallation of these conjugates yielded the complexes fac-[M(CO)₃(k³-L)]⁺ (M is ^99mTc/Re; 1/1a, L is L ¹ ; 2/2a, L is L ² ; 3/3a, L is L ³ ), with IC₅₀ values in the subnanomolar and nanomolar range. The MC1R-mediated internalization of 2 and 3 is higher than that of 1 in B16F1 melanoma cells. Biodistribution studies in melanoma-bearing mice have shown low nonspecific accumulation with a tumor uptake that correlates with IC₅₀ values. However, no correlation between tumor uptake and valency was found. Nevertheless, 2 displayed the highest tumor retention, and the best tumor to nontarget organ ratios.     

Synthesis,Molecular Conformation and Activity Against Herpes Simplex Virus of (E)-5-(2-Bromovinyl)-2′-Deoxycytidine Analogs

Analogs of (E)-5-(2-bromovinyl)-2 ′-deoxycytidine (BrVdCyd) (1) by substitution at N⁴ were synthesized to impart resistance against deamination. The anti-HSV-1 activity and solution conformation of these analogs were determined. N⁴-Acetyl-BrVdCyd (2) was a potent inhibitor of HSV-1 replication whereas N⁴-propanoyl-BrVdCyd (3) had good activity and N⁴-Butanoyl-BrVdCyd (4) had only low activity against HSV-1 replication. N⁴-Methyl-BrVdCyd (5) was devoid of activity against HSV-1.     

Plant regeneration from protoplasts ofCapsicum annuum L. cv. California Wonder

Plant regeneration from mesophyll protoplasts of pepper,Capsicum annuum L. cv. California Wonder has been demonstrated via shoot organogenesis. Protoplasts isolated from fully expanded leaves of 3-week-old axenic shoots when cultured in TM medium supplemented with 1 mg l ⁻¹ NAA, 1 mg l ⁻¹ 2,4-D, 0 5 mg l ⁻¹ BAP (CM 1) resulted in divisions with a frequency ranging from 20–25 %. Antioxidant ascorbic acid and polyvinylpyrrolidone (PVP) in the medium and incubation in the dark helped overcome browning of protoplasts. Microcalli and macrocalli were formed in TM medium containing 2 mg l ⁻¹ NAA and 0.5 mg l ⁻¹ BAP (CM II) and MS gelled medium containing 2 mg 1 ⁻¹ NAA and 0 5 mg 1 ⁻¹ BAP (CM III), respectively. Regeneration of plantlets was possible via caulogenesis. Microshoots, 2–5 percallus appeared on MS gelled medium enriched with 0.5 mg l ⁻¹ IAA, 2mg l ⁻¹ GA and l0mg l ⁻¹ BAP (CM IVc). Rooting of microshoots was obtained on half strength gelled medium containing 1 mg l ⁻¹ NAA and 0.5mg l ⁻¹ BAP. Protoplasts isolated from cotyledons failed to divide and degenerated eventually.     

Selective Metalation of 6-Methylpurines: Synthesis of 6-Fluoromethylpurines and Related Nucleosides

Abstract

A selective metalation at the 6-CH3 over C-8 of 6-methylpurine derivative 6 was observed with softer counter cation (Na⁺ or K⁺) of the base, while the harder Li⁺ showed no selectivity. In the presence of N-fluorobenzenesulfonamide (NFSI), this property was utilized for the synthesis of 6-fluoromethylpurine derivatives 4 and 5 as potential toxins for suicide gene therapy.     

Synthesis,characterization and inhibitory potency of two oxono and thiono analogues of phosphoramidate compounds on acetylcholinesterase

Two novel structurally related phosphoramidate compounds, 1 and 2, with likely β-diketone system were synthesized and characterized by ¹H, ¹³C, ³¹P NMR, IR spectroscopy and elemental analysis. Compound 2 exhibited a ³¹P NMR signal which was significantly shielded (8 ppm) relative to compound 1. Determination of human erythrocyte acetylcholinesterase (hAChE) inhibitory activity was carried out according to Ellman's modified kinetic method and the IC₅₀ values of compounds 1 and 2 were 1.567 and 2.986 mM, respectively. The k_i values of 1 and 2 were 1.39 to 2.65 min^{? 1} respectively. A comparison of the bimolecular rate constant (k_i) and IC₅₀ values for the irreversible inhibitors 1 and 2 revealed that the oxono analogue has greater affinity for hAChE than the thiono compound. Furthermore effects of two conventional oximes paralidoxime (A) and obidoxime (B) on reactivation of the inhibited hAChE were studied but low reactivity was shown by both the oximes.     

A Novel Zeolite Coating for Protection of Concrete Sewers from Biological Sulfuric Acid Attack

Microbial growth inhibition and resistance to biological deterioration of concrete specimens coated with silver-loaded zeolite was evaluated by measuring the time course of bacterial growth, biological sulfur oxidation, and sulfate production using Acidithiobacillus thiooxidans as a corrosive agent. Live bacterial cells declined from an initial inoculum concentration of 1.1 × 10₄ cell ml_-1 to zero in 10 days, during which only 0.5–1% of the initial sulfur concentration of 10 g l_-1 was biologically oxidized, corresponding to sulfate production rates of 35–42 mg SO ₄ ^{2 ?} g ^{? 1} S ^{? 1} . Leaching coefficients of calcium and silicon in the specimens coated with silver-loaded zeolite of 1.6 × 10 ^{? 4} to 4.6 × 10 ^{? 2} cm ² d ^{? 1} respectively, were only 0.8% and 1% of the uncoated specimens.     

Antifungal activity of a novel chromene dimer

The activity on Aspergillus spp. growth and on ochratoxin A production of two novel chromene dimers (3) was evaluated. The results of the bioassays indicate that the chromene dimer 3a inhibited mycelia growth by approximately 50% (EC₅₀) at 140.1 μmol L⁻¹ for A. niger, 384.2 μmol L⁻¹ for A. carbonarius, 69.1 μmol L⁻¹ for A. alliaceus and 559.1 μmol L⁻¹ for A. ochraceus. When applied at concentrations of 2 mmol L⁻¹, 3a totally inhibited the growth of all Aspergillus spp. tested. Furthermore, ochratoxin A production by A. alliaceus was reduced by about 94% with a 200 μmol L⁻¹ solution of this compound. A moderate inhibitory effect was observed for the analogous structure 3b on ochratoxin A production but not in mycelia growth. No inhibition was registered for compounds 2a and 2b, used as synthetic precursors of the dimeric species 3.     

PLD activation in Chinese hamster ovary (CHO) cells transfected with PGF2α receptor cDNA

Pertussis toxin-insensitive GTP-binding protein was observed to be involved in prostaglandin F2α(PGF2α)-induced phosphoinositide metabolism in Chinese hamster ovary (CHO) cells transfected with PGF2α receptor cDNA (CHO-PGF2α·R cells) (Ito, S. et al. Biochem. Biophys. Res. Commun. 200: 756, 1994). In the present study, we investigated PGF2α-induced PLD activation in CHO-PGF2α·R cells. PLD activation was examined by measuring the production of [³H]phosphatidylbutanol ([³H]PBut), a specific product of the PLD-catalyzed transphosphatidylation reaction. PGF2α-induced [³H]PBut formation was concentration-dependent with the maximal level obtained at 1 μM PGF2α. The maximal [³H]PBut formation was observed at 2 min after addition of PGF2α. Depletion of extracellular Ca²⁺ with EGTA suppressed PGF2α-induced PLD activation by 50%. PKC inhibitors Ro31–8425 and calphostin C inhibited PGF2α-induced [³H]PBut formation by 50%. PTK inhibitors genistein and herbimycin A failed to inhibit PGF2α-induced PLD activation. A combination of maximal effective concentrations of PGF2α (1 μM) and PMA (100 nM) enhanced PLD activation in an additive manner. Pretreatment of the cells with PMA for 2 h down-regulated PKCα and decreased PGF2α-induced PLD activation. These results suggest that PLD activation by PGF2α is mediated by both PKC-dependent and -independent pathways and that PKCα is involved in the former pathway.     

Patterns of soil and plant nitrogen isotope composition and their relationships with climate factors in Xilingol League,Inner Mongolia,China

Background: Plant and soil nitrogen stable isotope (δ¹⁵N) can integrate several fundamental biogeochemical processes in ecosystem nitrogen dynamics, and reflect characteristics of ecosystem nitrogen cycling.

Aims: We investigated how climate change influenced plant-soil nitrogen cycling by relating soil δ¹⁵N, plant δ¹⁵N and Δδ¹⁵N (difference between soil and plant δ¹⁵N) with climatic factors.

Methods: Field investigation was conducted in temperate grasslands in Inner Mongolia during August 2015. Plant δ¹⁵N, soil δ¹⁵N and Δδ¹⁵N were determined, and their relationships with climatic factors were examined by simple regression analyses and general linear models.

Results: Soil δ¹⁵N was significantly higher than plant δ¹⁵N, and there was a positive linear correlation between them. Soil and plant δ¹⁵N were negatively related with mean annual precipitation (MAP) and positively with mean annual temperature (MAT); conversely, Δδ¹⁵N was positively related with MAP and negatively with MAT.

Conclusion: Soil δ¹⁵N was dominantly controlled by MAT, while it was MAP for plant δ¹⁵N. Climate factors influenced plant δ¹⁵N not only through their effects on soil nitrogen dynamics but also strategies of plant nitrogen acquisition. Thus, compared with plant δ¹⁵N, soil δ¹⁵N can more accurately reflect soil nitrogen dynamics, while plant δ¹⁵N may integrate soil nitrogen dynamics and plant nitrogen acquisition.     

Calcium-dependent trapping of mitochondria near plasma membrane in stimulated astrocytes

Growing evidence suggests that astrocytes are the active partners of neurons in many brain functions. Astrocytic mitochondria are highly motile organelles which regulate the temporal and spatial patterns of Ca ²⁺ dynamics, in addition to being a major source of ATP and reactive oxygen species. Previous studies have shown that mitochondria translocate to endoplasmic reticulum during Ca ²⁺ release from internal stores, but whether a similar spatial interaction between mitochondria and plasma membrane occurs is not known. Using total internal reflection fluorescence (TIRF) microscopy we show that a fraction of mitochondria became trapped near the plasma membrane of cultured hippocampal astrocytes during exposure to the transmitters glutamate or ATP, resulting in net translocation of the mitochondria to the plasma membrane. This translocation was dependent on the intracellular Ca ²⁺ rise because it was blocked by pre-incubation with BAPTA AM and mimicked by application of the Ca ²⁺ ionophore ionomycin. Transmembrane Ca ²⁺ influx induced by raising external Ca ²⁺ also caused mitochondrial trapping, which occurred more rapidly than that produced by glutamate or ATP. In astrocytes treated with the microtubule-disrupting agent nocodazole, intracellular Ca ²⁺ rises failed to induce trapping of mitochondria near plasma membrane, suggesting a role for microtubules in this phenomenon. Our data reveal the Ca ²⁺ -dependent trapping of mitochondria near the plasma membrane as a novel form of mitochondrial regulation, which is likely to control the perimembrane Ca ²⁺ dynamics and regulate signaling by mitochondria-derived reactive oxygen species. Electronic Supplementary Materials Supplementary Materials is available in the online version of this article at     

Antioxidant activity of 5-alkoxymethyl-6-chromanols

Abstract

The 5-alkoxymethyl-2,2,7,8-tetramethyl-6-chromanols (II) are excellent antioxidants against autoxidising safflower oil (ASO), although not as good as 2,2,5,7,8-pentamethyl-6-chromanol (I), the model compound of -tocopherol. The aim of this work was to determine whether the rate of reaction of (II) with the radicals diphenylpicrylhydrazyl (DPP^·) and galvinoxyl (ArO^·) was directly proportional to their antioxidant activity against ASO. Compounds (II) reacted faster with DPP^·. than with ArO^·. but, in each case, slower than compound (I). The rates of reaction of I and II with both radicals followed the order I > II (R = H) > II (R = CH₃) > II (R = other alkyls) and were directly proportional to their antioxidant activity against ASO.     

A sugar-aza-crown ether-based fluorescent sensor for Cu and Hg ions

A sugar-aza-crown ether (SAC)-based fluorescent sensor 4 was prepared. It contains a pyrene as the fluorophore and its fluoroionophoric properties toward transition metal ions were investigated. Chemosensor 4 exhibits highly selective recognition toward Cu²⁺ and Hg²⁺ ions among a series of tested metal ions in methanol solution. The association constants for 4*Cu²⁺ and 4*Hg²⁺ in methanol solution were calculated to be 7.4 × 10¹ M⁻¹ and 4.4 × 10³ M⁻¹, respectively. Chemosensor 4 formed complexes with the Cu²⁺ or Hg²⁺ ion at a 1:1 ligand-to-metal ratio with a detection limit of 1.3 × 10⁻⁴ M Cu²⁺ and 1.26 × 10⁻⁵ M Hg²⁺, respectively.     

Interaction of (2′ -5′) and (3′ -5′) Linked 2-Aminoadenylyl-3-aminoadenosines with Polyuridylic Acid

Abstract

2′-5′ and 3′-5′ linked 2-aminoadenylyl-2-aminoadenosines [(2′-5′)n²Apn²A (1) and (3′-5′)n²Apn²A (2)] were synthesized by condensation of 5′-O-monomethoxytrityl-N ² N ⁶-dibenzoyl-2-aminoadenosine and N ²,N ⁶,2′,3′-O-tetrabenzoyl-2-aminoadenosine 5′-phosphate using dicyclohexylcarbodiimide (DCC). The conformational properties of these dimers 1 and 2 were examined by UV, NMR and CD spectroscopy. The results reveal that the 2′-5′-isomer 1 takes a stacked conformation, which contains a larger base-base overlap and is more stable against thermal perturbation with respect to the 3′-5′-isomer 2. Interactions of 1 and 2 with polyuridylic acid (Poly (U)) were also examined by Tm, mixing curves, UV and CD spectra. Both the dinucleoside isomers 1 and 2 formed a complex of 1 : 2 stoichiometry with poly(U), which was much more stable than that of the corresponding ApA isomer     

Sorption of Cadmium and Lead by Bacteria–Ferrihydrite Composites

The sorptive behavior of bacteria—iron oxide composites was investigated in batch metal sorption assays using ferrihydrite in isolation (0.13 and 0.14 g/L ferrihydrite in cadmium and lead systems, respectively) as well as in combination with Bacillus subtilis (0.25 g/L adsorbent mixture) and Escherichia coli (0.27 g/L adsorbent mixture). A pH range from 3.0 to 6.5 was studied using total metal concentrations of 1.0 × 10 ^{? 4.0} and 3.2 × 10 ^{? 5} M with adsorbent mixtures proportioned on a 1:1 mass/volume basis. The log of the apparent surface complex formation constants (log K ^S _M ) and sorption capacity (S _max ) values were determined by fitting the experimental data to one-site Langmuir sorption isotherms. The one-site model effectively described the sorption data (r ² > 0.9), where Cd ^{2 +} exhibited somewhat lower sorption affinities (log K ^S _M = ?3 for ferrihydrite, ?1.7 for B. subtilis–ferrihydrite, and ?1.1 for E. coli–ferrihydrite) than Pb ^{2 +} (log K ^S _M = ?0.9 for ferrihydrite, ? 0.2 forB. subtilis–ferrihydrite, and –0.1 for E. coli–ferrihydrite). The corresponding S _max values for Cd ^{2 +} and Pb ^{2 +} on ferrihydrite were 0.78 mmole/g and 1.34 mmole/g, respectively. For the B. subtilis–ferrihydrite composites, Cd ^{2 +} and Pb ^{2 +} S _max values were lower at 0.29 mmole/g and 0.5 mmole/g, respectively. Similar values were determined for the E. coli–ferrihydrite composites (0.15 mmole/g and 0.68 mmole/g for Cd ^{2 +} and Pb ^{2 +} , respectively). The sorption of Cd ^{2 +} and Pb ^{2 +} by each of the sorbent systems exhibited a strong dependence on pH with sorption edges in the range of pH 4.0 to 7.3. The observed S _max of the composites were lower than values predicted upon available site additivity (Cd ^{2 +} _{B. subtilis ?ferrihydrite} : 0.29 mmole/g (observed) < 0.57 mmole/g (calculated); Cd ^{2 +} _{E. coli ?ferrihydrite} : 0.15 mmole/g (observed) < 0.44 mmole/ g (calculated); Pb ^{2 +} _{B. subtilis ?ferrihydrite} : 0.5 mmole/g (observed) < 0.805 mmole/g (calculated); Pb ^{2 +} _{E. coli –ferrihydrite} : 0.68 mmole/g (observed) < 0.775 mmole/g (calculated)), implying that a masking of reactive surface sites by attachment had occurred between the bacteria and ferrihydrite. Electrophoretic mobility analysis indicated that the ferrihydrite surface properties dominate the net surface charge for each composite system with lesser contributions from the bacteria.     

Design, synthesis and DNA binding properties of orthogonally positioned diamino containing polyamide f-IPI

An orthogonally positioned diamino/dicationic polyamide f-IPI 2 was synthesized. It has enhanced binding affinity, and it showed comparable sequence specificity to its monoamino/monocationic counterpart f-IPI 1. Results from CD and DNase I footprinting studies confirmed the minor groove binding and selectivity of polyamides 1 and 2 for the cognate sequence 5′-ACGCGT-3′. SPR studies provided their binding constants: 2.4 × 10⁸ M⁻¹ for diamino 2, which is ∼4 times higher than 5.4 × 10⁷ M⁻¹ for its monoamino analogue 1.     

Synthesis and anticonvulsant activity of some 2-(2-{1-[substituted phenyl]ethylidene}hydrazinyl)-4-(4-methoxy-phenyl)-6-oxo-1,6-dihydro-pyrimidine-5-carbonitrile

A series of dihydro-pyrimidine-5-carbonitrile derivatives (3–16) were synthesized and evaluated for their anticonvulsant activity against MES and scPTZ models. Motor impairment screening was carried out by rotarod test method and CNS depressant effect was determined by Porsolt’s force swim pool method. Compounds 4 and 9 having p-substituted bromo and m-substituted nitro groups, respectively, were found to be most active showing activity both in MES and scPTZ screen at lower doses of 30 mgkg^?1 at 0.5?h and 100 mgkg^?1 at 4?h. In the rotarod motor impairment screen, compound 4 did not show any motor impairment even at the maximum dose of 300 mgkg^?1; however, compound 9 showed motor impairment at 300 mgkg^?1 dose after 4.0?h. The compounds were also tested for their CNS depression effect. The compounds 4 and 9 showed 41.38 and 43.44% increase in immobility time with respect to control. The pharmacophore hypothesis also fits best for compounds 4 and 9.     

Novel DPPH Radical Scavengers,Demethylbisorbibutenolide and Trichopyrone,from a Fungus

In our screening program for antioxidants with 1,1-diphenyl-2-picrylhydrazyl (DPPH)-radical scavenging activity, two novel compounds, demethylbisorbibutenolide (1) and trichopyrone (2), were isolated from the fermentation broth of the fungus of USF-4860 strain isolated from a soil sample. The structures of these compounds were determined from spectroscopic evidence. The biosynthetic origin of the carbon atoms of 2 was unambiguously determined by feeding experiments using ¹³C-labeled precursors and elucidation of the ¹³C-NMR spectrum of ¹³C-labeled 2. These studies showed that 2 was derived from five acetates and a methyl group of methionine. In the DPPH-radical scavenging assay, 1 and 2 gave ED₅₀ values of 149 and 167 μM after standing for 2.0 hr. Compound 2 reacted with the DPPH radical to form reaction product 3 which was determined to be 1-[4-(3,4-dihydro-3-methyl-6-{1,3-pentadienyl}-2,4-dioxo-2H-pyran-3-yl)-phenyl]-1-phenyl-2-picrylhydrazine from spectroscopic evidence.     

SYNTHESIS of 2′-DEOXY-2′-FLUOROGUANYL-(3′,5′)-GUANOSINE

ABSTRACT

The protected analogue of 2-amnio-6-chloropurine arabinoside (3b) was subjected to reaction with diethylaminosulfur trifluoride (DAST) and subsequently treated with NaOAc in Ac₂O/AcOH to give N ²,O ^3′,O ^5′-triacetyl-2′-deoxy-2′-fluoroguanosine (5a). After deacetylation of the sugar moiety and protection of 5′-OH by a 4,4′-dimethoxytrityl group, this nucleoside component was converted to 2′-deoxy-2′-fluoroguanyl-(3′,5′)-guanosine (6c, GfpG).