Isolation of two antifungal compounds fromNeolitsea cuipala and their activity against some plant pathogenic fungi

Zeylanidine and zeylanicine isolated fromNeolitsea cuipala fruit peels are found to be potential antifungal agents againstHelminthosporium oryzae, Fusarium oxysporum, Alternaria solani, Curvularia varuciformis andColletotrichum gleosporioides.     

Light meromyosin paracrystal formation

Studies of paracrystal formation by column purified light meromyosin (LMM) prepared in a variety of ways led to the following conclusions: (a) different portions of the myosin rod may be coded for different stagger relationships. This was concluded from observations that paracrystals with different axial repeat periodicities could be obtained either with LMM framents of different lengths prepared with the same enzyme, or with LMM fragments of identical lengths but prepared with different enzymes. (b) Paracrystals with a 14-nm axial repeat periodicity are most likely formed by the aggregation of sheets with a 44-nm axial repeat within the sheets which are staggered by 14 nm. All of the axial repeat patterns expected from one sheet or aggregates of more than one sheet, on this basis, were observed in the same electron micrograph. (c) C-protein binding probably occurs preferentially to LMM molecules related in some specific way. This was concluded from the observation that the same axial repeat pattern was obtained in paracrystals formed from different LMM preparations in the presence of C-protein, regardless of differences in the axial repeat obtained in the absence of C-protein. (d) Nucleic acid is responsible for the 43-nm axial repeat patterns observed in paracrystals formed by the ethanol-resistant fraction of LMM. In the absence of nuclei acid, paracrystals with a 14nm axial repeat are obtained. (e) The 43-nm axial repeat pattern observed with the ethanol-resistant fraction of LMM is different for LMM preparations obtained by trypsin and papain digestions.     

Cytotoxicity, mutations and DNA damage produced in Chinese hamster cells treated with streptozotocin, its analogs, and N-methyl-N'-nitro-N-nitrosoguanidine.

The activities of streptozotocin (SZ), three structural analogs of SZ, and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in producing cytotoxicity, mutations to 8-azaguanine (8-AzG) resistance, and DNA damage (single-strand breaks) in V79 Chinese hamster cells have been examined. These three biological processes appear to be associated. MNNG was about 10(3) times more active on a molar basis than SZ, and the activities of the analogs fell within these extremes.     

Small interfering RNAs mediate sequence-independent gene suppression and induce immune activation by signaling through toll-like receptor 3

Small interfering (si) and short hairpin (sh) RNAs induce robust degradation of homologous mRNAs, making them a potent tool to achieve gene silencing in mammalian cells. Silencing by siRNAs is used widely because it is considered highly specific for the targeted gene, although a recent report suggests that siRNA also induce signaling through the type I IFN system. When human embryonic kidney 293 (HEK293) or keratinocyte (HaCaT) cell lines or human primary dendritic cells or macrophages were transfected with siRNA or shRNAs, suppression of nontargeted mRNA expression was detected. Additionally, siRNA and shRNA, independent of their sequences, initiated immune activation, including IFN-alpha and TNF-alpha production and increased HLA-DR expression, in transfected macrophages and dendritic cells. The siRNAs induced low, but significant, levels of IFN-beta in HEK293 and HaCaT cells. Secretion of these cytokines increased tremendously when HEK293 cells overexpressed Toll-like receptor 3 (TLR3), and the increased secretion of IFN-beta was inhibited by coexpression of an inhibitor of TIR domain-containing adapter-inducing IFN-beta, the TLR3 adaptor protein linked to IFN regulatory factor 3 signaling. Although siRNA and shRNA knockdown of genes represents a new and powerful tool, it is not without nonspecific effects, which we demonstrate are mediated in part by signaling through TLR3.     

Pulmonary function and fuel use: A population survey

Background

In the backdrop of conflicting reports (some studies reported adverse outcomes of biomass fuel use whereas few studies reported absence of any association between adverse health effect and fuel use, may be due to presence of large number of confounding variables) on the respiratory health effects of biomass fuel use, this cross sectional survey was undertaken to understand the role of fuel use on pulmonary function.

Method

This study was conducted in a village of western India involving 369 randomly selected adult subjects (165 male and 204 female). All the subjects were interviewed and were subjected to pulmonary function test. Analysis of covariance was performed to compare the levels of different pulmonary function test parameters in relation to different fuel use taking care of the role of possible confounding factors.

Results

This study showed that biomass fuel use (especially wood) is an important factor for deterioration of pulmonary function (particularly in female). FEV₁ (p < .05), FEV₁ % (p < .01), PEFR (p < .05) and FEF_25–75 (p < .01) values were significantly lower in biomass fuel using females than nonusers. Comparison of only biomass fuel use vs. only LPG (Liquefied Petroleum Gas) use and only wood vs. only LPG use has showed that LPG is a safer fuel so far as deterioration of pulmonary function is concerned. This study observes some deterioration of pulmonary function in the male subjects also, who came from biomass fuel using families.

Conclusion

This study concluded that traditional biomass fuels like wood have adverse effects on pulmonary function.     

Folding of horse cytochrome c in the reduced state

Equilibrium and kinetic folding studies of horse cytochrome c in the reduced state have been carried out under strictly anaerobic conditions at neutral pH, 10 degrees C, in the entire range of aqueous solubility of guanidinium hydrochloride (GdnHCl). Equilibrium unfolding transitions observed by Soret heme absorbance, excitation energy transfer from the lone tryptophan residue to the ferrous heme, and far-UV circular dichroism (CD) are all biphasic and superimposable, implying no accumulation of structural intermediates. The thermodynamic parameters obtained by two-state analysis of these transitions yielded DeltaG(H2O)=18.8(+/-1.45) kcal mol(-1), and C(m)=5.1(+/-0.15) M GdnHCl, indicating unusual stability of reduced cytochrome c. These results have been used in conjunction with the redox potential of native cytochrome c and the known stability of oxidized cytochrome c to estimate a value of -164 mV as the redox potential of the unfolded protein. Stopped-flow kinetics of folding and unfolding have been recorded by Soret heme absorbance, and tryptophan fluorescence as observables. The refolding kinetics are monophasic in the transition region, but become biphasic as moderate to strongly native-like conditions are approached. There also is a burst folding reaction unobservable in the stopped-flow time window. Analyses of the two observable rates and their amplitudes indicate that the faster of the two rates corresponds to apparent two-state folding (U<-->N) of 80-90 % of unfolded molecules with a time constant in the range 190-550 micros estimated by linear extrapolation and model calculations. The remaining 10-20 % of the population folds to an off-pathway intermediate, I, which is required to unfold first to the initial unfolded state, U, in order to refold correctly to the native state, N (I<-->U<-->N). The slower of the two observable rates, which has a positive slope in the linear functional dependence on the denaturant concentration indicating that an unfolding process under native-like conditions indeed exists, originates from the unfolding of I to U, which rate-limits the overall folding of these 10-20 % of molecules. Both fast and slow rates are independent of protein concentration and pH of the refolding milieu, suggesting that the off-pathway intermediate is not a protein aggregate or trapped by heme misligation. The nature or type of unfolded-state heme ligation does not interfere with refolding. Equilibrium pH titration of the unfolded state yielded coupled ionization of the two non-native histidine ligands, H26 and H33, with a pK(a) value of 5.85. A substantial fraction of the unfolded population persists as the six-coordinate form even at low pH, suggesting ligation of the two methionine residues, M65 and M80. These results have been used along with the known ligand-binding properties of unfolded cytochrome c to propose a model for heme ligation dynamics. In contrast to refolding kinetics, the unfolding kinetics of reduced cytochrome c recorded by observation of Soret absorbance and tryptophan fluorescence are all slow, simple, and single-exponential. In the presence of 6.8 M GdnHCl, the unfolding time constant is approximately 300(+/-125) ms. There is no burst unfolding reaction. Simulations of the observed folding-unfolding kinetics by numerical solutions of the rate equations corresponding to the three-state I<-->U<-->N scheme have yielded the microscopic rate constants.