Biomedical subjects

Huixin Li

Publications and source records attributed to Huixin Li.

8 recordsLinked to original sources

PubMed2006

Characterization of the genes encoding UL24, TK and gH proteins from duck enteritis virus (DEV): a proof for the classification of DEV.

Duck enteritis virus (DEV) is classified to the family Herpesviridae, but has not been grouped into any genus so far. Four overlapped fragments were amplified from the DEV genome with polymerase chain reaction (PCR). The assembled length of the four fragments was 6,202 bp, which contained the genes encoding unique long (UL) 24, thymidine kinase (TK) and glycoprotein H (gH) proteins. The UL24 overlapped with TK by 64 nucleotides (nt), in a head-to-head transcription orientation, and the TK and gH had the same transcription orientation. The comparison of amino acid sequences of these 3 deduced DEV proteins with other 12 alphaherpesviruses displayed 5 highly conserved sites in the UL24, as well as another 5 consensus regions in the TK and 4 consensus regions in the gH. The RNA polymerase II transcriptional control elements were identified in all the UL24, TK and gH of DEV. These elements included core promoters, TATA motifs and polyadenylation sites. Phylogenetic analysis for the genetic classification of DEV in the Alphaherpesvirinae subfamily with other 12 alphaherpesviruses was computed. The result showed that DEV was more closely related to avian herpesviruses, except infectious laryngotracheitis virus (ILTV), than to other alphaherpesviruses. Conclusively, according to the phylogenesis-based analysis and the homology comparison of functional domains of UL24, TK and gH, DEV should be classified to a separate genus of the Alphaherpesvirinae subfamily in the family Herpesviridae.

Alphaherpesvirinae↗

PubMed2005

The influence of Al(III) supersaturation and NaOH concentration on the rate of crystallization of Al(OH)3 precursor particles from sodium aluminate solutions.

The growth kinetics of colloidal Al(III)-containing particles (diameter<1000 nm), nucleated in optically clear, supersaturated sodium aluminate solutions as a precursor to Al(OH)(3) crystals, has been studied using dynamic light scattering. Two series of solutions were examined at 22 degrees C to determine the influence of Al(III) supersaturation and NaOH concentration on the initial particle growth behavior. One solution series consisted of solutions with constant Al(III) absolute supersaturation (DeltaC) of 1.48 M and [NaOH] range 1.83-4.00 M ([NaOH]/[Al(III)]=1.13-2.15) and Al(III) relative supersaturation (sigma)=3.86-10.36. The other solution series had a constant sigma of 7.55 and [NaOH] range of 1.50-4.27 M ([NaOH]/[Al(III)]=1.18-1.54) and DeltaC=0.86-3.19. The correlation between the initial particle growth rates and supersaturation (DeltaC or sigma) revealed marked anomalies over the entire supersaturation range studied. The growth rate remained substantially constant in the DeltaC range 0.86-2.55 M (for the constant sigma solution series), before increasing sharply upon a further increase of DeltaC beyond 2.55 M. The variation of the growth rate with sigma in the range 3.86-9.00 (for the constant DeltaC solution series) was remarkably weak, contrary to expectation. At higher sigma (>9.00), however, a marked increase in growth rate with increasing sigma was displayed. At constant DeltaC or sigma, the growth rate showed a strong variation with NaOH concentration, indicating that Na(+) and OH(-) species play a pivotal role in the Al(OH) precursor particles (nuclei) growth process. Furthermore, the kinetics of growth displayed by these nanosized particles are an order of magnitude slower than those observed for macroscopic gibbsite (gamma-Al(OH)(3)) crystals at similar supersaturations and temperature. The difference may be rationalized in terms of particle size and Al(OH)(3) dimorphic phase dependent solubility effects. An empirically adequate growth kinetics modeling was achieved when the growth rates were correlated with the Al(III) supersaturation (DeltaC or sigma) and the excess (free) NaOH concentration, rather than the former alone, as is commonly the case. A critical [NaOH]/[Al(III)] molar ratio of 1.27-1.35, below which the particle growth rate increased markedly and above which the rate was significantly reduced, was observed. This behavior is believed to be linked to solution speciation change that occurs at certain Al(III) and NaOH compositions.

Journal Article↗

PubMed2005

Structural differences between light and heavy rare earth element binding chlorophylls in naturally grown fern: Dicranopteris linearis.

Chloroplasts and chlorophylls were isolated from the leaves of Dicranopteris linearis, a natural perennial fern sampled at rare earth element (REE) mining areas in the South-Jiangxi region (southern China). The inductively coupled plasma-mass spectrometry (ICP-MS) results indicated that REEs were present in the chloroplasts and chlorophylls of D. linearis. The in vivo coordination environment of light REE (lanthanum) or heavy REE (yttrium) ions in D. linearis chlorophyll-a was determined by the extended X-ray absorption fine structure (EXAFS). Results revealed that there were eight nitrogen atoms in the first coordination shell of the lanthanum atom, whereas there were four nitrogen atoms in the first coordination shell of yttrium. It was postulated that the lanthanum-chlorophyll-a complex might have a double-layer sandwich-like structure, but yttrium-binding chlorophyll-a might be in a single-layer form. Because the content of REE-binding chlorophylls in D. linearis chlorophylls was very low, it is impossible to obtain structural characteristics of REE-binding chlorophylls by direct analysis of the Fourier transform infrared (FTIR) and ultraviolet (UV)-visible spectra of D. linearis chlorophylls. In order to acquire more structural information of REE-binding chlorophyll-a in D. linearis, lanthanum - and yttrium-chlorophyll-a complexes were in vitro synthesized in acetone solution. Element analyses and EXAFS results indicated that REE ions (lanthanum or yttrium) of REE-chlorophyll-a possessed the same coordination environment whether in vivo or in vitro. The FTIR spectra of the REE-chlorophyll-a complexes indicated that REEs were bound to the porphyrin rings of chlorophylls. UV-visible results showed that the intensity ratios of Soret to the Q-band of REE-chlorophyll-a complexes were higher than those of standard chlorophyll-a and pheophytin-a, indicating that REE-chlorophyll-a might have a much stronger ability to absorb the ultraviolet light. The MCD spectrum in the Soret band region of lanthanum-chlorophyll-a showed a special peak, but yttrium-chlorophyll-a did not have this special peak, corresponding well to their double-layer and single-layer structure, respectively.

Chlorophyll↗

PubMed2005

[Effects of bacteria-feeding nematode at its different density on bacterial number, bacterial activity and soil nitrogen mineralization].

A gnotobiotic microcosm experiment was conducted to study the interactions between bacteria-feeding nematode Caenorhabditis elegans and bacterium Bacillus subtilis, and their effects on soil nitrogen mineralization at different Caenorhabditis elegans density. The results showed that the inoculation of the nematode stimulated the growth of the bacterium, and the increment was in order of 20>10>40 nematodes x g(-1) dried soil. The interaction between Caenorhabditis elegans and Bacillus subtilis significantly enhanced soil respiration rate and soil invertase, urease and phosphatase activities, with no significant differences among three test nematode densities. The inoculation of bacterial-feeding nematode markedly increased soil NH4+ -N and mineral N, suggesting that soil N mineralization was enhanced under the effect of the nematode. The increment of soil nitrogen mineralization at different nematode density was also in the same order mentioned above.

Animals↗

PubMed2004

[Effects of different vegetation restoration of degraded red soil on earthworm population dynamics].

This study was conducted at the long-term experimental plots in Ecological Experimental Station of Red Soil in Yujiang County (28 degrees 15'30''N, 116 degrees 55'30''E ), Jiangxi Province, subtropical China. Earthworm population was investigated seasonally from May 1999 to February 2000, under different vegetations including four artificial woodlands [deciduous broadleaf woodland (Quercus chenii, Qc), evergreen broadleaf woodland (Schima superba, Ss), coniferous woodland (Pinus massonina, Pm) and mixed woodland (Schima superba-Pinus massonina, Sm)], two grasslands [gently-disturbed grassland (G1), undisturbed grassland (G2)] and control wasteland (CK). The results indicated that the population structure was very simple. Only Drawinda gisti characterized by pioneer was found. The seasonal averages of density and biomass were in the order of G2 > G1 > Qc > Ss > Pm > Sm > CK, and those of G2, G1 and Qc were significantly higher than those of the latters (P < 0.05). Seasonal fluctuations were obvious with dry-hot summer depressing the earthworm population sharply, leading to the aestivation of earthworm. Based on the variation coefficients of density and biomass, Qc had the highest ecosystem stability, followed by Sm and Ss, and G1, G2, and Pm had the lowest stability. The overall differentiation of earthworm population could be drawn through canonical discriminant analysis. There were significant correlations between earthworms and some soil properties (P < 0.01). Overall, the differentiation of earthworm population was driven by the quantity and quality of soil organic matter returned by the vegetations. Additionally, based on earthworm population, the importance of selecting appropriate vegetation types during the restoration of degraded red soil was emphasized.

Animals↗

PubMed2004

[Interactions between fungal-feeding nematodes and fungi and their effects on soil nitrogen mineralization].

A species of fungal-feeding nematodes (Aphelenchus avenae) and two species of fungi (Micheli corticolus and Moniliaceae sp.) were isolated from an alluvial soil planted with paddy-rice and wheat in subtropical region. In order to approach their interactions and effects on soil nitrogen mineralization, a gnotobiotic microcosm experiment was carried out with four treatments, i.e., 1) soil + fungi-I (M. corticolus), 2) soil + fungi I + Aphelenchus avenae, 3) soil + fungi II (Moniliaceae sp.), and 4) soil + fungi II + Aphelenchus avenae at 22 degrees C for 25 days. The results showed that the individuals of nematode and fungi were increased simultaneously, suggesting that the inoculation of A. avenae stimulated the growth of fungi. The fungal-feeding nematode increased during the initial 20 days of incubation and then decreased slowly, and the individuals of the nematode that fed on Moniliaceae sp. (II) were higher than those fed on M. corticolus (I) (P<0.01). In the first 12 days of incubation, the population of Moniliaceae sp. (II) increased 2.5-3.5 times, while that of M. corticolus (I) increased slower but caught up after the 12th day, and the density reached 5.0-5.7 times higher than the corresponding treatments with only fungi inoculation. The interactions encouraged the soil nitrogen mineralization of all four treatments, as compared with the control. Comparing the treatments with and without fungal-feeding nematode inoculation, the treatments with fungal-feeding nematode had a higher content of soil NH4+-N than those with only fungi inoculations, which indicated that nematode had a greater effect on soil nitrogen mineralization than fungi. As for the two species of fungi, M. corticolus (I) had a greater effect on soil nitrogen mineralization than Moniliaceae sp. (II). It was observed, however, that the nitrification rate declined as compared with the control.

Animals↗

PubMed2003

[Effect of bacterivorous nematodes on bacteria population under gnotobiotic culture].

A gnotobiotic microcosm experiment was conducted to study the influence of bacterivorous nematodes (Protorhabditis sp.) on bacteria (Pseudomonas fluorescens) population under different conditions including substrate concentration, oscillation pattern, and numbers of nematodes inoculated. When the bacteria were incubated under intermittent oscillation by hand (6 times at 0.5 h intervals, 22 degrees C), their growth was stimulated in the presence of nematoedes, and the bacteria grew faster with the increase of nematode numbers and substrate (liquid potato-sucrose medium) concentration. However, when the incubation was under continuous oscillation (100 rpm, 22 degrees C), bacteria population was deflated with the addition of nematodes, and the inhibition was greater when a higher concentration of substrate was used. It was found that the stimulation or inhibition of bacteria population by nematodes occurred in the logarithmic stage of bacteria growth. The optimal and over-grazing of nematodes on regulating bacteria population was discussed.

Animals↗

PubMed2002

[Effect of earthworm inoculation on soil carbon and nitrogen dynamics and on crop yield with application of corn residues].

This study was carried out in the Experimental Station of Nanjing Agricultural University, which is in a subtropical monsoon region characterized by a warm-wet spring and a hot-dry summer. The annual average temperature, precipitation and evaporation are 15.6 degrees C, 1010 mm and 1560 mm, respectively. In 1999, the experimental plots (2.8 m x 1.0 m x 0.6 m) were established by concrete frame. Soil in the plots was orthic aquisols collected from Rugao County, Jiangsu Province. Crop rotation was upland rice and winter wheat. At the beginning of the first crop (rice) season, earthworms (Pheretima sp.) were inoculated at a density of 10.m-2 and 20.m-2, respectively, in the plots with an application of corn residues at the rate of 1500 g.m-2(750 g.m-2 in the following seasons). The responses of soil carbon and nitrogen and crop yield to earthworm activity were investigated from 1999 to 2001. The results showed that earthworms had no significant influences on total soil carbon and nitrogen content, which implied that there was no depletion of soil carbon and nitrogen pools in the presence of earthworms. The maintenance of soil carbon might be explained by low assimilation efficiency of organic matter by earthworms, and by the compensation of carbon returning from plant production enhancement. Soil mineral nitrogen, soil microbial biomass carbon and microbial biomass nitrogen were increased, and nitrogen mineralization was strengthened by earthworm activities, which was more obvious at jointing/booting and heading stages. In comparison with no-worm treatments, the yield of rice wheat increased by 9.3% and 5.1%, respectively, in the treatments inoculated with earthworms. It was concluded that earthworm was very important in promoting nitrogen recycling of crop residues and plant productivity, and in keeping the balance of soil carbon pool as well.

Agriculture↗