The host species affects the microbial community in the goat rumen

AIMS

This study was carried out to determine whether bacterial and ciliate populations in goat rumen vary significantly between different goat species living in the same environment.

METHODS AND RESULTS

Bacterial and ciliate communities in the rumen of three goat species were analysed at the molecular level using denaturing gradient gel electrophoresis. The microbial community varied considerably among goats living in the same environment. Interspecies variation in the bacterial population was noticeably greater than intraspecies variation. In contrast, there was considerable variation in the ciliate population among goats within the same species, and intraspecies similarities were no greater than those observed across species.

CONCLUSIONS

Because environmental factors and diets were identical for all goats, differences in bacterial populations reflect species-specific differences in rumen microbes.

SIGNIFICANCE AND IMPACT OF THE STUDY

Factors related to the host species have an important effect on determining the bacterial composition in the goat rumen.

Negative refractions in two-dimensional photonic crystals formed by holographic lithography

We present a study on negative refractions in the four lowest bands of two-dimensional (2D) square lattices formed by holographic lithography (HL) and compare these features with those of a lattice of the same kind but with regular dielectric columns. The plane wave calculations and FDTD simulations have shown that in some bands or for some interfaces the negative refraction can only happen in holographic structures, and generally the rightness of holographic structures and regular structures of the same kind may be different.

Introduction of a disulfide bridge enhances the thermostability of a Streptomyces olivaceoviridis xylanase mutant

Substitution of the N-terminus of Streptomyces olivaceoviridis xylanase XYNB to generate mutant TB has been previously shown to increase the thermostability of the enzyme. To further improve the stability of this mutant, we introduced a disulfide bridge (C109-C153) into the TB mutant, generating TS. To assess the effect of the disulfide bridge in the wild-type enzyme, the S109C-N153C mutation was also introduced into XYNB, resulting in XS. The mutants were expressed in Pichia pastoris, the recombinant enzymes were purified, and the effect of temperature and pH on enzymatic activity was characterized. Introduction of the disulfide bridge (C109-C153) into XYNB (XS variant) and TB (TS variant) increased the thermostability up to 2.8-fold and 12.4-fold, respectively, relative to XYNB, after incubation at 70 degrees C, pH 6.0, for 20 min. In addition, a synergistic effect of the disulfide bridge and the N-terminus replacement was observed, which extended the half-life of XYNB from 3 to 150 min. Moreover, XS and TS displayed better resistance to acidic conditions compared with the respective enzymes that did not contain a disulfide bridge.

Holographic design and band gap evolution of photonic crystals formed with five-beam symmetric umbrella configuration

We propose a holographic design of five-beam symmetric umbrella configuration, where there are a central beam and four ambient beams symmetrically scattered around the central one with the same apex angle, for fabrication of three-dimensional photonic crystals with tetragonal or cubic symmetries, and systematically analyzed the band gap properties of resultant photonic crystals when the apex angle is continuously increased. Our calculations reveal that large complete photonic band gaps exist in a wide range of apex angle for a relatively low refractive index contrast. Specifically, the face-centered cubic structure with a relative band gap of 25.1% for epsilon = 11.9 can be obtained with this recording geometry conveniently where all the beams are incident from the same half-space. These results will provide us with more understanding of this important recording geometry and give guidelines to its use in experiments.

Two-step phase-shifting interferometry and its application in image encryption

Conventional phase-shifting interferometry (PSI) needs at least three interferograms. A novel algorithm of two-step PSI, with an arbitrary known phase step, by which a complex object field can be reconstructed with only two interferograms is proposed. This algorithm is then applied to an information security system based on double random-phase encoding in the Fresnel domain. The feasibility of this method and its robustness against occlusion and additional noise attacks are verified by computer simulations. This approach can considerably improve the efficiency of data transmission and is very suitable for Internet use.

Growth inhibition of cancer cells by an active metabolite of a novel vitamin D prodrug

Active vitamin D compounds have been developed that maintain antiproliferative properties with low calcemic activity. BCI-210, a novel vitamin D pro-drug developed in our laboratory, is activated through side chain hydroxylation and possesses lower calcemic activity than calcitriol. The human hepatoma cell line (HepG2) was used to produce an active metabolite, which was characterized and identified as 27-hydroxy-BCI-210. We compared the ability of 27-OH-BCI-210 with calcitriol to inhibit proliferation of prostate (LNCaP), and breast (MCF-7) cancer cells. Cells were plated in multi-well plates and incubated with vehicle or vitamin D compounds for 6 days, after which the cell numbers were determined by a colorimetric assay. 27-OH-BCI-210 produced a dose-dependent growth inhibition, although a concentration five-fold greater than calcitriol was required to produce equivalent inhibition. We also examined the antiproliferative activity of 27-OH-BCI-210 in combination with chemotherapeutic drugs. With genistein and doxorubicin, 27-OH-BCI-210 produced synergistic inhibition of proliferation of LNCaP and MCF-7 cells. These synergistic interactions suggest the potential clinical utility of 27-OH-BCI-210 in the treatment of prostate and breast tumors.

Larger bandgaps of two-dimensional triangular photonic crystals fabricated by holographic lithography can be realized by recording geometry design

The photonic band gap (PBG) properties of two classes of two-dimensional (2-D) triangular lattice fabricated by holographic lithography are investigated numerically. The effect of intensity threshold on the filling ratio and then the shape of "atoms", and the corresponding photonic gap are comprehensively studied. Our results show that the recording geometry for a given 2-D triangular lattice is not unique, and this fact gives us more freedom in choosing proper recording geometry to obtain larger bandgap.

Search for extraterrestrial point sources of neutrinos with AMANDA-II

We present the results of a search for point sources of high-energy neutrinos in the northern hemisphere using AMANDA-II data collected in the year 2000. Included are flux limits on several active-galactic-nuclei blazars, microquasars, magnetars, and other candidate neutrino sources. A search for excesses above a random background of cosmic-ray-induced atmospheric neutrinos and misreconstructed downgoing cosmic-ray muons reveals no statistically significant neutrino point sources. We show that AMANDA-II has achieved the sensitivity required to probe known TeV gamma-ray sources such as the blazar Markarian 501 in its 1997 flaring state at a level where neutrino and gamma-ray fluxes are equal.

Interference of four umbrellalike beams by a diffractive beam splitter for fabrication of two-dimensional square and trigonal lattices

A simple optical interference method for fabricating two-dimensional square and trigonal lattices is demonstrated. A general formula for the interference contrast formed by two arbitrary polarized elliptical waves is deduced, the relation between wave vectors of incident light and the resultant pattern is analyzed, and polarization optimization of all beams to ensure uniform contrast is given.

Formation of three-dimensional periodic microstructures by interference of four noncoplanar beams

A newly reported method of making three-dimensional microstructures or photonic crystals by holographic lithography has some obvious advantages over other techniques with the same purpose. A systematic and comprehensive analysis of interference of four noncoplanar beams (IFNB) is provided. It shows that all 14 Bravais lattices can be formed by means of IFNB and gives explicit relationships between each lattice and the corresponding recording geometry. The concept of pattern contrast is extended to the case of IFNB, and it is indicated that a uniform contrast for each interference term can be obtained by properly choosing the beam ratio and polarization. A calculation algorithm is then developed to optimize the direction of polarization of each beam to ensure maximum uniform contrast. These results, verified by computer simulations, may lay a theoretical foundation for fabrication of photonic crystals with the approach of IFNB.

All fourteen Bravais lattices can be formed by interference of four noncoplanar beams

The interference of four noncoplanar beams (IFNB) is analyzed. It is shown that all 14 Bravais lattices can be formed by a holographic method of IFNB. The relationship among the three basis vectors of the lattice that are to be produced, the required wavelength, and the geometric arrangement of the four beams is derived. This analysis may lay the foundation for fabrication of three-dimensional photonic crystals by holographic lithography.

Expression of Human Trefoil Factor 3 in Pichia pastoris and Its Biological Activity Analysis

The human TFF3 (trefoil factor 3) DNA fragment was amplified by polymerase chain reaction (PCR) from human fetal placenta cDNA. The gene was cloned into the Pichia pastoris expression vector pPIC9K containing AOX 1 promoter and alpha-factor leader sequence. Multi-copies insertion transformants were screened on G418 plates. After the induction by 2% methanol for 48 hours, the expression of dimeric hTFF3 came up to 45% of total proteins in medium, as identified by SDS-PAGE and Western blot assay. The recombinant protein was further purified by S-Sepharose, Q-Sepharose ion-exchange chromatography and Sephacryl-S-100 gel filtration chromatography to the 95% purity, as shown by densitometric scanning. The N-terminus and molecular weight of the recombinant hTFF3 was in good agreement with the native hTFF3. The recombinant protein was proved to have good biological activity of preventing rats from the gastric ulcer induced by hydrochloric acid.

Formation of a microfiber bundle by interference of three noncoplanar beams

A systematic analysis of interference of three noncoplanar plane waves with identical frequency is provided. This analysis shows that a fiber bundle with spacing of the order of the wavelength, which one may conveniently control by changing the recording geometry, can be formed by this means. The relation between the incident light-wave vectors and the resultant pattern is analyzed. The concept of uniform contrast for an interference pattern is introduced, and the polarization optimization approach for each beam that ensures maximum uniform contrast for each beam is also given.

[Studies on the expression condition of human trefoil factor 3 in Pichia pastoris]

In order to enhance the expression level of human trefoil factor 3 (hTFF3) in Pichia pastoris, we optimized the transformant growth conditions in shake flasks including carbon sources in growth medium, inoculation ratio, methanol concentration, pH rotation speed and inducing time. The transformant could grow on the glucose to OD600 5.0 after 14 hours inoculation. The best inoculation ration of 100 mL growth medium to the induction medium was 1:1. The expression level of dimeric human trefoil factor 3 induction with 1% methanol for 48 hours at pH 6.0, agitation speed 240 r/min could reach 20 mg/L with OD600 15. The protein was expressed in 5-liter fermentor with 2% methanol induction for 32 hours, finally the cell density reached OD600 120. 100 mg/L of recombinant hTFF3 was obtained in the supernatant.

Zinc status affects p53, gadd45, and c-fos expression and caspase-3 activity in human bronchial epithelial cells

This study was designed to examine the influence of zinc depletion and supplementation on the expression of p53 gene, target genes of p53, and caspase-3 activity in normal human bronchial epithelial (NHBE) cells. A serum-free, low-zinc medium containing 0.4 micromol/l of zinc [zinc deficient (ZD)] was used to deplete cellular zinc over one passage. In addition, cells were cultured for one passage in media containing 4.0 micromol/l of zinc [zinc normal (ZN)], which represents normal culture concentrations (Clonetics); 16 micromol/l of zinc [zinc adequate (ZA)], which represents normal human plasma zinc levels; or 32 micromol/l of zinc [zinc supplemented (ZS)], which represents the high end of plasma zinc levels attainable by oral supplementation in humans. Compared with ZN cells, cellular zinc levels were 76% lower in ZD cells but 3.5-fold and 6-fold higher in ZA and ZS cells, respectively. Abundances of p53 mRNA and nuclear p53 protein were elevated in treatment groups compared with controls (ZN). For p53 mRNA abundance, the highest increase (3-fold) was observed in ZD cells. In contrast, the highest increase (17-fold) in p53 nuclear protein levels was detected in ZS cells. Moreover, gadd45 mRNA abundance was moderately elevated in ZD and ZA cells and was not altered in ZS cells compared with ZN cells. Furthermore, the only alteration in c-fos mRNA and caspase-3 activity was the twofold increase and the 25% reduction, respectively, detected in ZS compared with ZN cells. Thus p53, gadd45, and c-fos and caspase-3 activity appeared to be modulated by cellular zinc status in NHBE cells.

[Cloning of neutral phytase gene nphy from Bacillus subtilis and its expression in Escherichia coli]

The gene encoding the neutral phytase nphy was cloned from Bacillus subtilis by polymerase chain reaction (PCR). Nucleotide sequence analysis of nphy revealed the presence of an open reading frame of 1152 bp coding for 383 aa. The start codon was followed by a sequence coding for a putative signal peptide of 26 aa in length. The nphy without original signal peptide encoding sequence was cloned into E. coli expression plasmid pTYB40. The result of SDS-PAGE of the phytase expressed in E. coli showed that the nphy had been overexpressed. The expressed phytase was over 40% of the total soluble protein of E. coli, and has normal bioactivity.

[The mechanism of macrophage apoptosis induced by lipopolysaccharide in mice]

Apoptosis is a major form of cell death, characterized morphologically by chromatin condensation and biochemically by endonuclease cleavage of DNA into oligonucleosomal fragments. We investigated apoptosis mechanism of peritoneal macrophage(M phi) induced by peritoneal injection of lipopolysaccharide(LPS) in mice. The results showed that: LPS induced the apoptosis of peritoneal M phi and concomitant decrease of phagocytosis(vs control group, P < 0.01), the concentration of NO2-/No3- in the peritoneal lavage fluid significantly increased after LPS injection; AG(inhibitor of iNOS) and PDTC(inhibitor of reactive oxygen species) prevented the apoptosis of M phi and reduced the concentration of NO2-/NO3- in the peritoneal lavage fluid. In vitro experiment, we found that AG and PDTC inhibited the apoptosis of M phi induced by IFN(100 U.ml-1) + LPS (10 micrograms.ml-1) by using DNA gel electrophoresis analysis. These evidences support that NO and active oxygen species may be involved in the apoptosis process of peritoneal M phi induced by LPS in mice.

[Determination of six ginsenosides in Panax species by high performance liquid chromatography]

A method for the determination of six major ginsenosides in panax species by high performance liquid chromatography (HPLC) with UV detection at 203 nm is described. The six major ginsenosides, which were reported to account for more than 90% of the total ginsenosides content of the panax species' root, were successfully separated using gradient HPLC. The column to be used was a Cosmosil-C18 reversed-phase, 4.6 mm i.d. x 250 mm, 5 microns (Japan), connected with a C18 guard column and the mobile phase was acetonitrile and water. The calibration curves of the six ginsenosides were all linear over the range of 25 mg/L-300 mg/L with good correlation coefficients (> 0.99). The recoveries for the ginsenosides were all above 80%. For real samples and recovery study, the major ginsenosides were ultrasonically extracted by methanol. The extracts were evaporated to 1 mL, under vacuum, at about 50 degrees C and then diluted by methanol. Just prior to HPLC analysis, the sample solutions were filtered using a C18 cartridge. This method has been successfully applied to the analysis of four commercial panax samples.

Regulation of intestinal apolipoprotein B mRNA editing levels by a zinc-deficient diet and cDNA cloning of editing protein in hamsters

This study was conducted to investigate the influence of dietary zinc on intestinal apoB mRNA editing in hamsters. Apolipoprotein B-48 (apoB-48) is synthesized from the same gene as apoB-100 by a post-transcriptional, site-specific cytidine deamination, a process known as apoB mRNA editing. A cDNA encoding the hamster apoB mRNA editing enzyme was obtained by reverse transcriptase-polymerase chain reaction (RT-PCR) and the deduced amino acid sequence was found to possess high amino acid sequence identity to apoB mRNA editing enzymes from several other species. Editing activity was detected in the small intestine and colon but, like humans, none was detected in the liver. Analysis by RT-PCR indicated that the small intestine possessed the highest expression of editing enzyme mRNA abundance, whereas both liver and small intestine expressed relatively high levels of apoB mRNA. The influence of dietary zinc on intestinal apoB mRNA editing levels was examined in Golden Syrian hamsters (7 wk old) assigned to one of the following three dietary treatments: Zn-adequate (ZA, 30 mg Zn/kg diet), Zn-deficient (ZD, <0. 5 mg Zn/kg diet), or Zn-replenished (ZDA, ZD hamsters receiving ZA diet for last 2 d) for 7 wk. Hamsters consuming the ZD diet had modestly but significantly lower intestinal editing activity than ZA hamsters. Intestinal editing activity in the ZDA group was not different from that of ZA hamsters. Data derived from these studies contribute to the understanding of lipoprotein metabolism in hamsters, a suitable model for the study of atherosclerosis.

Expression of the p53 tumor suppressor gene is up-regulated by depletion of intracellular zinc in HepG2 cells

Expression and activation of the p53 tumor suppressor protein are modulated by various cellular stimuli. The objective of this work was to examine the influence of zinc depletion on the expression of p53 in HepG2 cells. Two different low Zn (ZD) media, Zn-free Opti-MEM and a ZD medium containing Chelex-100 treated serum, were used to deplete cellular zinc over one passage. Cellular zinc levels of ZD cells were significantly lower than in their controls in both the Opti-MEM and Chelex studies. p53 mRNA abundance was 187% higher in ZD Opti-MEM cells and >100% higher in ZD Chelex cells compared with their respective controls. To examine whether the effects were specific to zinc depletion, a third, zinc-replenished group (ZDA) was included in the Opti-MEM study in which cells were cultured in ZD media for nearly one passage before a change was made to zinc-adequate (ZA) medium for the last 24 h. Zinc levels in the ZDA cells were significantly higher than in ZD cells, and p53 mRNA abundance was normalized to control levels. Nuclear p53 protein levels were >100% higher in the ZD Opti-MEM cells than in ZA cells. Interestingly, the ZDA Opti-MEM cells had significantly lower levels of nuclear p53 protein than both the ZA and ZD cells. These data suggest that expression of p53, a critical component in the maintenance of genomic stability, may be affected by reductions in cellular zinc.

[A study on screening and high density cell cultivation of a yeast strain Kluyveromyces with high inulinase yielding and its enzymology properties]

A yeast strain Kluyveromyces with high inulinase yield was screened. The highest inulinase activity of 288.78 u/mL was reached when a high cell density cultivation method was developed for inulinase production. It was 6.8 times higher than the highest level reported in the same species. The activity ratio of its inulinase to invertase was 1/24.72, the Km values were 13.3 mmol/L and 62.6 mmol/L when inulin and sucrose were used as substrate, respectively; The optimum pH value was 4.4, this enzyme also showed a good pH adaptability and stability, i.e. more 90% of the highest level was maintained between pH 3.8 and 5.6; The optimum reaction temperature was 55 degrees C, higher activity was maintained between 50-57.5 degrees C, its half life period was 16 hours at 55 degrees C; It was found for the first time that addition of magnesium ion into the reaction system increased the enzyme activity by 11%.

Plasma apolipoprotein B-48, hepatic apolipoprotein B mRNA editing and apolipoprotein B mRNA editing catalytic subunit-1 mRNA levels are altered in zinc-deficient rats

Apolipoprotein B (apoB) exists as two major isoforms and serves as an obligatory component of lipid-rich plasma lipoprotein particles. Apolipoprotein B mRNA editing is a zinc-dependent, site-specific cytidine deamination that determines whether the apoB-100 or apoB-48 isoform is synthesized. The objective of this work was to examine whether dietary zinc levels affect apoB mRNA editing in vivo. Adult male Sprague-Dawley rats were randomly assigned to zinc-deficient (ZD, <0.5 mg Zn/kg diet), zinc-adequate (ZA, 30 mg Zn/kg diet) or zinc-replenished (ZDA, ZD rats fed the ZA diet for last 2 d) dietary groups for 18 d. The ratio of plasma apolipoprotein B-48 (apoB-48) to total apoB was significantly lower in zinc-deficient compared with zinc-adequate rats. Primer extension analysis indicated a modest but significant reduction in hepatic apoB mRNA editing in ZD rats compared with that of the ZA group. In ZDA rats, hepatic apoB mRNA editing and the percentage of plasma apoB-48 to total apoB were not different from ZA rats. The mRNA abundance of hepatic apobec-1 (apoB mRNA editing catalytic subunit 1) was significantly lower in ZD and ZDA rats than in ZA rats. In summary, the plasma ratio of apoB-48 to total apoB protein as well as hepatic apoB mRNA editing and hepatic apobec-1 mRNA levels were reduced in rats consuming a zinc-deficient diet. These data suggest that one or more components of apoB metabolism may be influenced by dietary zinc status.

Apolipoprotein A-I gene expression is regulated by cellular zinc status in hep G2 cells

The influence of Zn on the expression of the apolipoprotein A-I (apoA-I) gene in Hep G2 cells was examined. Zn depletion was achieved with a low-Zn (ZD) medium prepared from Zn-free growth medium (Opti), a ZD medium containing Chelex 100-extracted fetal bovine serum (CHE), and a medium containing chelator 1, 10-phenanthroline (OP). Compared with those for their respective controls, cellular Zn levels were reduced by 55, 48, and 46% and apoA-I mRNA abundances were reduced by 20, 29, and 28% in Opti, CHE, and OP systems, respectively, after one passage in ZD media or 24 h in OP medium. To establish the specificity of Zn treatment, groups of ZD cells were treated with their respective control media for the last 24 h (ZDA) or normal cells were cultured with OP medium supplemented with Zn (OP-Zn). ZDA treatments partially normalized cellular Zn levels in the Opti system and restored or elevated apoA-I mRNA levels in the Opti or CHE system, respectively. Similarly, the OP-Zn treatment restored the cellular Zn and apoA-I mRNA levels. Furthermore, one passage of culture with Zn-supplemented media in both the Opti and CHE systems resulted in higher cellular Zn and apoA-I mRNA levels than those for controls. Most significantly, short-term high-Zn induction to normal cells markedly elevated the cellular Zn (3-fold) and apoA-I mRNA (5-fold) levels. Data derived from this study strongly suggest that the expression of apoA-I is regulated by cellular Zn status.

[Study of formula for calculating body surface areas of the Chinese adults]

The body surface area of 100 Chinese adults (50 for each sex) was measured with the paper cast method and compared to the results estimated by the Stevenson's "height-weight-surface" formula. Our results shows that Stevenson's formula is no longer suitable for the Chinese. Our formulae for Chinese are as follows: SI=0.0061 x H + 0.0124 x W - 0.0099 (for both sexes), SII=0.0057 x H + 0.0121 - W + 0.0882 (for male), SIII=0.0073 H + 0.0127 x W - 0.2106 (for female) H: body height, W: body weight, S: body surface area