作者机构：
[Sun, X] E China Normal Univ, Coll Life Sci, Shanghai 200062, Peoples R China.;Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Peoples R China.;UMC, Div Biol Sci, Columbia, MO 65211 USA.
通讯机构：
[Sun, X] E;E China Normal Univ, Coll Life Sci, Shanghai 200062, Peoples R China.
摘要：
The present study explores the forward masking of the two-tone stimuli in sequence that evoked responses in the inferior colliculus (IC) of the echolocating bats. The results indicate that forward masking is obvious in the acoustic responses of the IC neurons to the two-tone stimuli. Meanwhile the intensity sensitivity of the neurons responding to the probe increases with the inter-tone interval decreasing. The effects of forward masking are correlated with the relative intensity and the interval between the masker and probe. That is, the effects of forward masking are reduced with the masker intensity decreasing and enhanced with the probe intensity decreasing and the inter-tone interval shortened. The present study suggests that there is a correlation between the characteristics of the response to the probe and the dynamic conditions of the postsynaptic currents in the IC neurons.
摘要：
Diurnal photosynthesis of Nostoc flagelliforme was investigated at varied levels of CO2 concentrations and desiccation in order to estimate the effects of enriched CO2 and watering on its daily production. Photosynthetic activity was closely correlated with the desiccated status of the algal mats, increased immediately after watering, reached a maximum at moderate water loss, and then declined with further desiccation. Increased CO2 concentration enhanced the diurnal photosynthesis and raised the daily production. Watering twice per day enhanced the daily production due to prolonged period of active photosynthesis. The values of daily net production were 1321280 mumol CO2 g (d. wt)(-1) d(-1), corresponding to about 0.6-6.1% daily increase in dry weight. High-CO2-grown mats required higher levels of photon flux density to saturate the alga's photosynthesis in air. Air-grown mats showed higher photosynthetic affinity for CO2 and higher levels of dark respiration compared with high-CO2-grown samples.
摘要：
By using a combined closed and free-fleld stimulation system, binaurality and azimuth tuning of the neurons in the auditory cortex of the big brown bat, Eptesicus fuscus, were studied. A variety of azimuth-tuning functions were demonstrated for the binaural neurons. The large majority of EE (contralateral and ipsilateral excitatory) neurons exhibited azimuth selectivity with the best azimuths (BA) at contralateral 30degrees-40degrees, some at ipsilateral 20degrees-40degrees and preferred azimuth ranges (PAR, response amplitude >75% of maximum) between 8degrees and 40degrees. Sound source azimuths strongly modulate spike counts with a mean modulation depth of 83.8% for EE neurons. El (contralateral excitatory and ipsilateral inhibitory) neurons have simple azimuth tuning with BA located at contralateral 20degrees-40degrees and a broad PAR ranged from 30degrees to 55degrees. The present results suggest that azimuth-tuning characteristics of binaural neurons in the auditory cortex of the bat are of significance for acoustic behaviour.
摘要：
The results of ecological investigation of Microcystis blooms and their toxicity in a eutrophic park pond (where the annual average of total nitrogen and total phosphorus was 6.1 mg (.) L-1 and 1.79 mg (.) L-1, respectively) are presented. The blooms were mainly contributed by M. aeruginosa occurring in the period from May to October when water temperature ranged from 16 to 33 degreesC. Three remarkable growth peaks of Microcystis during the period were observed with chlorophyll a level of 0.73 mg (.) L-1, 1.44 mg (.) L-1, and 1.30 mg (.) L-1, respectively. The blooms were independent of phosphorus, but highly dependent on ammonium. A level of ammonium of 9.5 mg (.) L-1 could trigger the outbreak of the bloom, while that below 0.89 mg (.) L-1 could inhibit its formation. In other words, ammonium in higher concentrations could promote blooming, while that in lower concentrations could be inhibitory. Microcystis toxicity tended to increase with the blooming process, but the toxic peaks lagged behind their corresponding growth peaks.
作者机构：
Zhongshan Univ, State Key Lab Biocontrol, Guangzhou 510275, Peoples R China.;Cent China Normal Univ, Inst Entomol, Wuhan 430079, Peoples R China.;Cent China Normal Univ, Vet Coll, Wuhan 430070, Peoples R China.;[Chen, XH; Yang, L; Long, QX; Wang, XZ] 中山大学;[Chen, QH] 华中师范大学昆虫学研究所
通讯机构：
State Key Laboratory for Biocontrol, Zhongshan University, China
期刊：
Journal of Applied Phycology,2002年14(5):423-429 ISSN：0921-8971
通讯作者：
Liu, ZL
作者机构：
[Liu, ZL] Nanjing Univ, Coll Life Sci, Jiangsu 210093, Peoples R China.;Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Hubei, Peoples R China.
通讯机构：
[Liu, ZL] N;Nanjing Univ, Coll Life Sci, Jiangsu 210093, Peoples R China.
摘要：
Ge-Xian-Mi (an edible species of Nostoc) grows in some mountain paddy fields in China during winter and forms macroscopically visible subspherical colonies. The geology and climate at one of its locations, Hefeng County, were investigated, and the present-day situation of Ge-Xian-Mi was assessed in order to raise awareness that it may be endangered. There were formerly 796 ha of rice fields suited to its growth in Hefeng County and the maximum annual yield ever reached was 25 t. The annual mean temperature is about 12.2degreesC, and the annual rainfall is 1934 mm with mean relative humidity of 78-87%. The distribution of Ge-Xian-Mi was found to be associated with the source of water and the pH values of water suited to its growth were 6.2-6.3. Soils in its habitats were enriched with phosphorus and contained more microbes than those without its distribution. With changing agricultural techniques most of the habitats are endangered or already extinct. The widespread use of herbicides, pesticides and fertilizers containing chlorine had been suggested to be an important factor limiting its distribution. The taxonomic identity of Ge-Xian-Mi is discussed.
摘要：
Microcystis aeruginosa Kutz. 7820 was cultured at 350 and 700 muL.L-1 CO2 to assess the impacts of doubled atmospheric CO2 concentration on this bloom-forming cyanobacterium. Doubling Of CO2 concentration in the airflow enhanced its growth by 52%-77%, with pH values decreased and dissolved inorganic carbon (DIC) increased in the medium. Photosynthetic efficiencies and dark respiratory rates expressed per unit chl a tended to increase with the doubling of CO2. However, saturating irradiances for photosynthesis and light-saturated photosynthetic rates normalized to cell number tended to decrease with the increase of DIC in the medium. Doubling of CO2 concentration in the airflow had less effect on DIC-saturated photosynthetic rates and apparent photosynthetic affinities for DIC. In the exponential phase, CO2 and HCO3- levels in the medium were higher than those required to saturate photosynthesis. Cultures with surface aeration were DIC limited in the stationary phase. The rate of CO2 dissolution into the liquid increased proportionally when CO2 in air was raised from 350 to 700 muL.L-1, thus increasing the availability of DIC in the medium and enhancing the rate of photosynthesis. Doubled CO2 could enhance CO2 dissolution, lower pH values, and influence the ionization fractions of various DIC species even when the photosynthesis was not DIC limited. Consequently, HCO3- concentrations in cultures were significantly higher than in controls, and the photosynthetic energy cost for the operation of CO2 concentrating mechanism might decrease.
作者机构：
[Jen, PHS] Univ Missouri, Div Biol Sci, Columbia, MO 65211 USA.;E China Normal Univ, Dept Biol, Shanghai, Peoples R China.;Cent China Normal Univ, Dept Biol, Wuhan, Peoples R China.
通讯机构：
[Jen, PHS] U;Univ Missouri, Div Biol Sci, Columbia, MO 65211 USA.
摘要：
This electrophysiological study tests the hypothesis that one possible neural pathway for corticofugally inhibited neurons in the central nucleus of the inferior colliculus (ICc) of the big brown bat, Eptesicus fuscus, is mediated through excitatory projections from the auditory cortex (AC) to the external nucleus of the IC (ICx), which then sends inhibitory inputs to the ICc. This study shows that all neurons in the ICx are broadly tuned to stimulus frequency. Electrical stimulation in the AC typically increases the number of impulses, expands the auditory spatial response areas, and broadens the frequency tuning curves (FTCs) of neurons in the ICx. This corticofugal facilitation is mediated at least in part through NMDA receptors, since application of DL-2-amino-5-phosphonovaleric acid (APV), an antagonist for NMDA, decreases these response properties of neurons in the ICx. Electrical stimulation in the ICx typically decreases the number of impulses, reduces the auditory spatial response areas, and narrows the FTCs of neurons in the ICc. This inhibition is mediated at least in part through GABAA receptors, since application of bicuculline, an antagonist for GABA, increases these response properties of neurons in the ICc. These data suggest that corticofugal facilitation of the ICx and the inhibition of the ICx to the ICc may be one of the polysynaptic pathways for corticofugal inhibition of neurons in the ICc. Possible functions of this polysynaptic pathway in acoustic orientation and signal processing are discussed.
摘要：
Photosynthetic responses of rewetted Nostoc flagelliforme to CO2, desiccation, light and temperature were investigated under emersed conditions in order to characterize its ecophysiological behaviour in nature. Net photosynthesis increased to a maximum rate at about 30 % water loss, then decreased, while dark respiration always decreased with the progress of desiccation. Light-saturated photosynthesis and dark respiration were significantly reduced at 8°C, but remained little affected by changes of temperature within the range of 15-35°C. Photosynthetic efficiency (α) was maximal at the beginning of desiccation and then reduced with increased water loss. Saturating irradiance for photosynthesis was about 194-439 μmol quanta m-2 s-1, being maximal at about 30 % water loss. No photoinhibition was observed at irradiances up to 1140 μmol m-2 s-1. Light compensation points were about 41-93 μmol m-2 s-1. Photosynthesis of N. flagelliforme was CO2-limited at the present atmospheric CO2 level. The CO2-saturated photosynthesis increased with increase of irradiance (190-1140 μmol m-2 s-1) and temperature (8-25°C) and decreased significantly with water loss (0-75 %). Photosynthetic affinity for CO2 was sensitive to temperature and irradiance. The CO2 compensation point (Γ) increased significantly with increased temperature and was insensitive to irradiance. Desiccation did not affect F values before water loss exceeded 70 %. Photorespiratory CO2 release did not occur in N. flagelliforme at the current atmospheric CO2 level.
作者机构：
[Yang, X] Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Peoples R China.;New Jiang Han Univ, Sch Med, Dept Publ Hlth, Wuhan 430014, Peoples R China.;Wuhan Publ Hlth & antiepidem Stn, Dept Environm Hlth, Wuhan 430022, Peoples R China.
通讯机构：
[Yang, X] C;Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Peoples R China.
关键词：
室内装修;胶合板;室内空气污染物;甲醛;眼部刺激;人体接触控制试验
摘要：
Obejective: The present study focuses on health assessment of wood based panels which are widely used in interior decoration practices over the recent years in China. Formaldehyde has been identified as chemical indicator of (IAO) and an indoor air pollutant. To test its health effects experiment was undertaken. Method: A small environmental test chamber (60/L) was used as the generator of emission gas from new panels, and was operating at a temperature of 22.7 ± 0.6°C and a humidity of 44.4 ± 2.5 % with an air exchange rate of 1.0 ± 0.15h-1. On the three experimental days the values of product loading in chamber were 4, 2 and 6 m2/m3, respectively. Eight people were selected randomly from the students and employees of Wuhan Health and Anti-epidemic Station as subjects, with an average age of 21.9 ± 5.9 years, and a gender ratio of 1:1, and two of them were smokers (one male and one female). The subjects' eyes were exposed to formaldehyde through a pair of goggles. Each goggle had its flow inlet and outlet, and connected to chamber exhaust of emission gas and to an exhaust from the room. The exposure time was very short, just 5 minutes and the formaldehyde doses were at 1.65 ± 0.01, 2.99 ± 0.07 and 4.31 ± 0.02 ppm. A 60-mm linear visual analogue rating scales was used to measure the intensity of sensory eye irritation and a video tape recorder was used to record eye blinking frequency. Results: The results demonstrated that tests of sensory eye irritation and eye blinking can be used for materials testing, and that a dose-effect as well as a time-variance of the effect can be measured. Conclusion: The tests showed that eye irritation was perceived at all of the three levels.
作者机构：
[Guo, HL] Wuhan Univ, Coll Life Sci, Wuhan 430072, Peoples R China.;Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Peoples R China.
通讯机构：
[Guo, HL] W;Wuhan Univ, Coll Life Sci, Wuhan 430072, Peoples R China.
关键词：
cyanobacterium;pH;vacuole
摘要：
Six species or strains of cyanobacteria, Anabaena sp. 595, Plectonema boryanum 246, Scytonema hofmanni 248, Nostoc sp. 96, Oscillatoria animlis 284 and Spirulina maxima 438, were cultured in unfavorable pH conditions for vacuole induction. At pH 5.0, 6.5, or 7.0, vacuoles were observed to form in both Anabaena sp. 595 and Plectonema boryanum 246, especially in the former. The vacuolation took place with some morphological changes, such as the cells being inflated, spherical and vacuolated, and with unequalized division. The induced vacuoles in Anabaena sp. 595 and Plectonema boryanum 246 were in spherical shape and in rather transparent appearance under a phase microscope. For Scytonema hofmanni 248, it was less sensitive to pH, its vacuole formation was found only at pH 6.5. No vacuolization occurred in the cells of Nostoc sp. 96, Oscillatoria animlis 284 and Spirulina maxima 438 at all pH conditions we used. Vacuolization under unfavorable pH provides a new proof for the existence of vacuole in cells of cyanobacteria and reflects the prokaryote's function in ecological environment.
作者机构：
[Zhu, YG] Wuhan Univ, Coll Life Sci, Wuhan 430072, Peoples R China.;Cent China Normal Univ, Coll Life Sci, Wuhan 430079, Peoples R China.
通讯机构：
[Zhu, YG] W;Wuhan Univ, Coll Life Sci, Wuhan 430072, Peoples R China.
关键词：
rice;HL cytoplasmic male sterility;restorer gene;microsatellite marker
摘要：
Bulked segregant analysis (BSA) of a BC, population derived from Congguang 41A//Miyang 23/Congguang 41B was used to map the nuclear fertility restorer gene for Honglian (HL) cytoplasmic male sterility. One hundred and fifty-nine microsatellite primer pairs were screened for polymorphisms between the parents and between two bulks representing fertile and sterile plants. One microsatellite marker RM258 produced polymorphic products. The nuclear fertility restorer gene for HL cytoplasmic male sterility was mapped on chromosome 10, 7.8cM from RM258. The restorer gene may be clustered on chromosome.
摘要：
The nucleocapsid protein gene (vp39) of a Chinese isolate of Bombyx mori nucleopolyhedrovirus (BmNPV-Ch), namely an open reading frame CORF) of 1050 bp that codes for a polypeptide of 39 K (VP39) consisting of 350 amino acids was sequenced. The homology of the nucleotide (nt) anti am ino acid sequences of vp39 and VP39, respectively, of BmNPV-Ch and a Japanese iso late of BmNPV (BmNPV-Ja) were found to be 97.5% and 97.1%, respectively. The BmNPV-Ch vp39 is nine nucleotides longer than that of BmNPV-Ja vp39 due to insertion of CGA at nt 625 and GTCGGC at nt 985-910. There are differences in 17 nucleotides causing a few substitutions of amino acids which slightly modify the secondary structure of BmNPV-Ch. It indicates that the main part of the secondary structure of VP39 is a Folded structure containing high proportion of beta -sheet and beta -turn units. A clot blot hybridization analysis revealed the existence of a homologous transcript of BmNPV-Ch vp39 in Sm cells infected with Autographa californica multiple nucleocapsid nucleopolyhedrovirus (AcMNPV).
摘要：
This study examines the effect of pulse repetition rate (PRR), pulse intensity, and bicuculline on the minimum threshold (MT) and latency of inferior collicular neurons of the big brown bat, Eptesicus fuscus, under free-field stimulation conditions. It tests the hypothesis that changes in MT and latency of collicular neurons are co-dependent on PRR. The number of impulses in inferior collicular neurons (n = 245) increased either monotonically (25%) or non-monotonically (75%) with pulse intensity. Latencies either decreased to a plateau (72%), fluctuated unpredictably within 3 ms (21%) or changed very little (7%) with increasing pulse intensity. Latencies and MTs of most collicular neurons increased by 1.5-24 ms (mean +/- SD = 4.8 +/- 3.3 ms) and 4-75 dB (mean +/- SD = 22.1 +/- 16.2 dB) with increasing PRR. In most neurons (94%), the latency increase was completely (42%) or partially (52%) eliminated when pulse intensity was compensated for the MT increase with PRR. Complete elimination of latency was achieved by bicuculline application. In a few neurons (6%), the latency increase with PRR was not affected by compensated pulse intensity or bicuculline application.
作者机构：
HUAZHONG NORMAL UNIV,DEPT BIOL,WUHAN 430070,PEOPLES R CHINA.;UNIV TSUKUBA,DEPT APPL BIOCHEM,TSUKUBA,IBARAKI 305,JAPAN.;[Tomura, D; Shoun, H] Department of Applied Biochemistry, University of Tsukuba, Ibaraki 305, Japan;[Liu, DL] Department of Biology, Huazhong Normal University, Wuhan, 430070
关键词：
cDNA cloning;Cytochrome P-460nor;Expression
摘要：
Cytochrome P-450nor is involved in the fungal denitrification and acts as a nitric oxide reductase. Tha cDNA library from Cylindrobarpon tonkinense was constructed with λgtll, and screened with antibodies. From the positive clones, the P-400nor2 cDNA fragments were recovered, and subcloned into the expression vector pYES2, then expressed in the yeast system. Western-blot analysis showed that the expressed protein, was hybridized with the antibody. Enzyme assay indicated that the expressed protein had the activities of P-450nor2, which reduced NO to form N2O, employing NADH or NADPH as the sole electron donor.
