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1.
Although biofilm formation may promote growth, biofilms are not always beneficial to their hosts. The biofilm formation characteristics of Bacillus cereus WPySW2 and its changes at different temperatures were studied. Results show that B. cereus WPySW2 promoted the growth of Neoporphyra haitanensis (an economically cultivated seaweed) at 20 °C but accelerated algal rot at 28 °C. Thicker B. cereus WPySW2 biofilms covered the surface of N. haitanensis thalli at 28 °C, which hindered material exchange between the algae and surrounding environment, inhibited algal photosynthesis and respiration, and accelerated algal decay. Compared with planktonic bacteria, mature biofilm cells had lower energy consumption and metabolic levels. The biofilm metabolic characteristics of B. cereus WPySW2 changed significantly with temperature. High temperature accelerated biofilm maturation, which made it thicker and more stable, allowing the bacteria to easily adapt to environmental changes and obtain greater benefits from their host. High temperature did not affect the production or increased the abundance of toxic metabolites, indicating that the negative effects of B. cereus WPySW2 on algae were not caused by toxins. This study shows that increased temperature can transform a harmless bacterium into a detrimental one, demonstrating that temperature may change the ecological function of phycospheric bacteria by affecting their morphology and metabolism.
相似文献2.
Pyropia yezoensis(formerly Porphyra yezoensis) is an economically important red alga that is cultured extensively in China. The red rot disease occurs commonly during Pyropia cultivation,causing serious economic losses. An incidence of red rot disease was found in a P. yezoensis farm from mid-November to mid-December 2015 at Lianyungang, Jiangsu Province, China. Histopathological examination revealed that the naturally infected thalli were infected apparently by a pathogen, leading to red rot symptoms. The causative agent was isolated and identified as the oomycete Pythium chondricola by morphological analysis and sequence analysis of the internal transcribed spacer and cytochrome oxidase subunit 1(cox1). In artificial infection experiments on the P. yezoensis blades, the P. chondricola isolate was able to cause the same characteristic histopathology seen in natural infections. P. chondricola grew well at a wide range of temperatures in the range 8-31℃, salinities at 0-45 and pH 5-9. In an orthogonal test used to determine the effects of environmental factors(temperature, salinity, and zoospore concentration)on infection, the data revealed that temperature was the most important factor to affect red rot disease development, with the optimal conditions for disease expansion being 20℃, 35 salinity, and a zoospore concentration of 10~6 zoospores/mL. The results obtained from the present study prompted us to set up a comprehensive epidemiological study on Pyropia, which will provide support to maintain the healthy development of the Pyropia industry in China. 相似文献
3.
Carla BOSSARD 《山地科学学报》2011,8(6):794-807
This paper reports the first photosynthetic study of marestail in Jiuzhaigou. In this work, we used PAM fluorometry to examine
photosynthetic rates of submerged and emerged marestail in three lakes. Three lakes were studied across a gradient of water
temperature, with low water temperature conditions in Grass Lake and Arrow Bamboo Lake, and higher water temperature in Five
Colored Lake. In the field, electron transport rates (ETRmax) were measured as rapid light curves (RLCs) by in situ yield measurements. Submerged and emerged marestail showed higher
photosynthetic activity in Five Colored Lake compared to the other lakes, a response consistent with the adaptation of marestail
in Five Colored Lake to high water temperature. The optimal temperature for photosynthesis of submerged marestail in Jiuzhaigou
was about 12 °C. Nonphotochemical quenching (NPQ) of submerged and emerged marestail increased with increasing water temperature.
Maximum quantum yield (F
v/F
m) of submerged marestail in Five Colored Lake showed full recovery at 1700 h due to higher NPQ. Further, the chlorophyll a for submerged marestail was the highest in Grass Lake and the lowest in Five Colored Lake. These results indicate that in
different lakes the function of these aquatic plants is associated with a diversity of place-dependent environmental conditions,
especially water temperature that leads to pronounced differences in the plant’s ecophysiological reactions. 相似文献
4.
The relationships between the neon flying squid, Ommastrephes bartrami, and the relative ocean environmental factors are analyzed. The environmental factors collected are sea surface temperature
(SST), chlorophyll concentration (Chl-a) and sea surface height (SSH) from NASA, as well as the yields of neon flying squid in the North Pacific Ocean. The results
show that the favorable temperature for neon flying squid living is 10°C–22°C and the favorite temperature is between 15°C–17°C.
The Chl-a concentration is 0.1–0.6 mg/m3. When Chl-a concentration changes to 0.12–0.14 mg/m3, the probability of forming fishing ground becomes very high. In most fishing grounds,
the SSH is higher than the mean SSH. The generalized additive model (GAM) was applied to analyze the correlations between
neon flying squid and ocean environmental factors. Every year, squids migrate northward from June to August and return southward
during October–November, and the characteristics of the both migrations are very different. When squids migrate to the north,
most relationships between the yields and SST are positive. The relationships are negative when squids move to southward.
The relationships between the yields and Chl-a concentrations are negative from June to October, and insignificant in November. There is no obvious correlation between
the catches of squid and longitude, but good with latitude.
Supported by the National High Technology Research and Development Program of China (863 Program, No. 2003AA607030); National
Key Technology Research and Development Program (No. 2006BAD09A05) 相似文献
5.
Vibrio harveyi cells (dose—<103 cells mL−1) and extracellular products (ECP; >25 μmg mL−1 of total protein concentration) destroyed haematopoietic cultures of Nephrops norvegicus within 24 h of exposure. Cytopathic effects (CPE) started after 4h of exposure to the bacterial cells, with some granularity
in the cytoplasm, mostly in cells in the outer periphery of the explant growth. At the end of the infection, a considerable
number of nuclei remained attached to the substrate, apparently unaffected. Following exposure to ECP, initial deterioration
was observed at 2 h with the presence of granularity in the cytoplasm of<20% cells, and few cells displayed small vacuoles
around the nuclei. Parallel results were obtained using whole animal experiments, with V. harveyi cells being lethal to nephrops within 24 h. 相似文献
6.
We evaluated the effect of water temperature on the growth and physiology of the Chinese longsnout catfish (Leiocassis longirostris Günther). The fish were reared at four temperatures (20, 25, 30, and 35°C) and sampled on days 7, 20, and 30. We measured plasma levels of insulin, free thyroxine (FT4), free 3,5,3′-triiodothyronine (FT3), lysozyme and leukocyte phagocytic activity. The optimum water temperature for growth was 27.7°C. The plasma levels of insulin and FT4 declined significantly (P<0.05) on day 30 at temperatures above 20°C. Lysozyme activity was significantly (P<0.05) lower at 25°C than at other temperatures. We conclude that final weight, insulin, FT4, and lysozyme were significantly affected by water temperature. 相似文献
7.
This pathogenic study shows that the viral diseases of Chinese prawns (Penaeus chinensis, O'sbeck) is due to three kinds of viruses: epithelium envelope baculovirus ofPenaeus chinensis (EEBV-PC, detected by the authors in 1993), infections hypodermal and hematopoietic necrosis virus, and hepatopancreatic
parvo-like virus, and that the first two viruses seem to be the main pathogens of the epidemic in the northern regions in
1993. 相似文献
8.
Maximum rate of food consumption ( Cmax ) was determined for juvenile Sebastodes fuscescens (Houttuyn) at water temperature of 10, 15, 20 and 25℃. The relationships of Cmax to the body weight (W) at each temperature were described by a power equation: lnCmax = a b lnW. Covariance analysis revealed significant interaction of the temperature and body weight. The relationship of adjusted Cmax to water temperature (T) was described by a quadratic equation: Cmax = -0.369 0.456T - 0.0117T^2. The optimal feeding temperature calculated from this equation was 19.5 ℃. The coefficients of the multiple regression estimation relating Cmax to body weight (W) and water temperature (T) were given in the Table 2. 相似文献
9.
Sori formation inLaminaria japonica was studied from the ecological and physiological point of view. Cutting through the medulla ofLaminaria japonica improved the formation of sori. Sori formation under different water temperature, photoperiod, and light intensity was investigated
and total nitrogen and reducible sugar content determined. The result showed that sori ofL. japonica can be formed in 1–22°C water in Dalian. No sori were found in water over 23°C. High temperature inhibits the formation of
sori, but low temperature has no effect. Apparently, light intensity affects the formation of sori, but photoperiod does not.
In shallow waterL. japonica grows slower but stores dry material faster and forms sori rapidly. In deeper water it grows faster in length but stores
dry material slower and the sori formation is slow. Analysis of dry material shows that during sori formation the water content
decreases but total nitrogen and total reducible sugar increase. Only when the storage of sugar reaches a certain level can
sori begin to form. Cutting through the medulla interrupts the passage of nutrients to the growth area. Storage of carbohydrates
and nitrogen is the main factor affecting sori formation. 相似文献
10.
Expression of putative zinc-finger protein lcn61 gene in lymphocystis disease virus China （LCDV-cn） genome 总被引：1，自引：0，他引：1
An open reading frame (lcn61) of lymphocystis disease virus China (LCDV-cn), probably responsible for encoding putative zinc-finger proteins was amplified
and inserted into pET24a (+) vector. Then it expressed in E. coli BL21 (DE3), and His-tag fusion protein of high yield was obtained. It was found that the fusion protein existed in E. coli mainly as inclusion bodies. The bioinformatics analysis indicates that LCN61 is C2H2 type zinc-finger protein containing
four C2H2 zinc-finger motifs. This work provides a theory for functional research of lcn61 gene.
Supported by High Technology Research and Development Program of China (863 Program, No. 2006AA100309) 相似文献
11.
The complex empirical orthogonal function is employed to analyse the monthly sea surface temperature anomalies (SSTA) in the
Tropical West Pacific (TWP) for the period from 1951 to 1986. The results show that the SSTA in the area appear in three patterns:
a quasi-stationary mode, a latitudinally propagating mode and a longitudinally propagating mode. The three modes contribute
almost equally to the total variance of SST. Digital filtering, time-lag correlation, etc., are applied to analyse the quasi-period
low frequency oscillations of the modes and their relations to the southern oscillation (SO) and the West Pacific Subtropical
High (WPSH).
The SSTA in the TWP is different from that in an ocean current area and plays a special role in the large scale air-sea interaction.
Aside from being related to the SSTA in the Equatorial East Pacific, the SSTA in the TWP, on the one hand, respond to the
oscillation of the global sea level pressure and influence the Subtropical High, and on the other hand receive feedback from
the Subtropical High.
This paper was published in Chinese inOceanologia et Limnologia Sinica
21 (2): 97–104, 1990. 相似文献
12.
The correlation between water quality parameters and hyper-spectral reflectance is studied with models established for each parameter and applied in Dianshan Lake, in the upstream of the Huangpu River running through Shanghai, China. Models are for dissolved oxygen (DO in mg/L): R720/R680 = 20.362×(R720/R680)2-31.438×(R720/R680)+19.156; for turbidity (NTU): R*714.5 = 206.07× (R*714.5)2-582.5×R*714.5 + 423.24; and for total phosphorus (TP in mg/L): R*509.5 = 16.661× (R*509.5)2-32.646×R*509.5+16.116. The R2 values are 0.770 8, 0.660 4 and 0.738 7, respectively, showing strong positive relationships. The models were then applied to assess water quality of different times. Results are quite satisfactory for some samples. 相似文献
13.
王小华 《中国海洋湖沼学报》1995,13(2):147-154
Studies of dynamics in Albatross Bay, the Gulf of Carpentaria, Australia, show strong tides of which M_2is the dominant constituent in the region. Tidal fronts are present and they can be modeled by a 2-Dtidal model. Density currents have also been observed with seasonal variations due to the influence ofwet or dry seasons. This paper reviews the effects of these dynamics on the migration of prawn postlarvae in AlbatrossBay and its estuaries. It is found that through its vertical movement triggered by change of salinity theprawn postlarvae can be transported from the coast to the estuary by tides within 2.8 weeks. Howeverthis horizontal displacement mechanism may be destroyed by the tidal front in Albatross Bay. Densitycurrents may alter prawn postlarvae positions in Albatross Bay on a seasonal scale. 相似文献
14.
Rotifer community structure was investigated in Yangcheng Lake in 2008. Dominant species and species diversity indices were determined and QB/T was used to assess water quality. The annual average density and biomass of the rotifers in Yangcheng Lake was 2 894 ± 1 006 ind./L and 12.47 ± 10.28 mg/L, respectively. The highest densities were observed in the western portion of the lake in March, but the highest biomass occurred in inflowing creeks in September. Within a year of monitoring in Yangcheng Lake, 93 species were identified and the dominant species were found to be Polyarthra trigla, Brachionus angularis, Keratella cochlearis, Keratella valga, Brachionus calyciflorus, and Filinia major. Of the species recorded, 75 were pollution indicator species. Density and biomass exhibited significant positive correlations with water temperature (R = 0.209, P = 0.003; R = 0.446, P = 0.000), but the peak density showed two lags in response to chl a. According to the Jaccard similarity index (SJ), the greatest similarity among dominant species occurred between creeks and the eastern part of the lake. The annual average Shannon-Wiener diversity index H’, Margalef richness index D and Pielou evenness index J were 1.96 ± 0.34, 1.61 ± 0.50 and 0.77 ± 0.10, respectively. In all four areas of Yangcheng Lake, β- mesosaprobic species comprised the largest share of pollution indicator species. These data suggest that Yangcheng Lake is mesosaprobic. 相似文献
15.
Variations of snow temperature and their influence on snow cover physical parameters in the Western Tianshan Mountains, China 总被引：1，自引：1，他引：0
This article discussed about snow temperature variations and their impact on snow cover parameters. Automatic temperature
recorders were used to sample at 10-minute intervals at the Tianshan Station for Snow-cover and Avalanche Research, Chinese
Academy of Sciences. 10-layer snow temperature and the snow cover parameters were measured by the snow property analyzer (Snow
Fork) in its Stable period, Interim period and Snow melting period. Results indicate that the amplitude of the diurnal fluctuation in the temperature during Snow melting period is 1.62 times greater than that during Stable period. Time up to the peak temperature at the snow surface lags behind the peak solar radiation by more than 2.5 hours, and lags
behind the peak atmospheric temperature by more than 0.2 hours during all three periods. The optimal fitted function of snow
temperature profile becomes more complicated from Stable period to Snow melting period. 22 h temperature profiles in Stable period are the optimal fitted by cubic polynomial equation. In Interim period and Snow melting period, temperature profiles are optimal fitted by exponential equation between sunset and sunrise, and by Fourier function when
solar radiation is strong. The vertical gradient in the snow temperature reaches its maximum value at the snow surface for
three periods. The peak of this maximum value occurs during Stable period, and is 4.46 times greater than during Interim period. The absolute value of temperature gradient is lower than 0.1°C cm−1 for 30 cm beneath snow surface. Snow temperature and temperature gradient in Stable period∼Interim period indirectly cause increase (decrease) of snow density mainly by increasing (decreasing) permittivity. While it dramatically
increases its water content to change its permittivity and snow density in Snow melting period. 相似文献
16.
Georg Heygster 《中国海洋大学学报(英文版)》2009,8(1):9-14
An algorithm to detect tropical deep convective clouds and deep convective overshootings based on the measurements from the three water vapor channels (183.3GHz±1 GHz, 183.3GHz±3GHz and 183.3GHz±7GHz) of the Advanced Microwave Sounding Unit-B (AMSU-B) is presented. This algorithm is an improved version of the method of Hong et al. (2005). The proposed procedure is based on the statistical analysis of seven years'(2001-2007) measurements from AMSU-B on NOAA-16 From the 1-d histograms of the brightness temperature of the three water vapor channels and the 2-d tustograms of the brightness temperature dif-ference between these channels, new thresholds for brightness temperature differences and the brightness temperature of channel 18 (183.3 GHz±1 GHz) are suggested. The new algorithm is employed to investigate the mean distribution of tropical deep convective clouds and convective overshootings from 30°S to 30°N for the years 2001 to 2007. The major concentration of deep convective clouds and convective overshootings is found over the Intertropical Convergence Zone (ITCZ), the South Pacific Convergence Zone (SPCZ), tropical Africa, South America, the Indian Ocean and Indonesia with an average fraction of 0.4%. In terms of these clouds we identify the secondary Intertropical Convergence Zone located in the eastern South Pacific and parallel to the main ITCZ in the North Pacific. The convective overshooting is more frequently observed over land than over the ocean. 相似文献
17.
This study showed that the combined effect of absorption of planktonic algae and water on water color shift can be simulated
approximately by the exponential function: Log(E
100cm
W
+E
100cm
Xch1
)=0.002λ−2.5 whereE
100 cm
W
,E
100cm
Xchl
are, respectively, extinction coefficients of seawater and chlorophyll—a (concentration is equal toX mg/m3), and λ (nm) is wavelength.
This empirical regression equation is very useful for forecasting the relation between water color and biomass in water not
affected by terrigenous material. The main factor affecting water color shift in the ocean should be the absorption of blue
light by planktonic algae. 相似文献
18.
1 INTRODUCTION White shrimp Litopenaeus vannamei, a tropical species, naturally distributes along the eastern Pa- cific coast from northern Mexico to northern Peru along 20℃ isotherms, was introduced into China in 1988 (Cai and Chen, 1995). Temperature w… 相似文献
19.
In laboratory conditions, effects of rearing temperature and stocking density were examined on hatching of fertilized egg
and growth of auricularia larvae of Apostichopus japonicus respectively. Data series like larval length and density, metamorphic time, and survival rate of the larvae were recorded.
Statistics showed that for A. japonicus, survival rate (from fertilized egg to late auricularia) decreased significantly with the increasing rearing temperature
(P<0.05). At different temperatures SGR was statistically significant as well (P<0.05) from day 1, and maximal SGR was found on day 9 at 24°C (159.26±3.28). This study clearly indicated that at low temperature
(<24°C), metamorphic rate was remarkably higher than at higher temperature (>26°C). Hatching rate was significantly different
between 0.2–5 ind./ml groups and 20–50 ind./ml groups. Rearing larvae at the higher density had the smaller maximal-length,
whereas needed longer time to complete metamorphosis. This study suggested that 21°C and 0.4 ind./ml can be used as the most
suitable rearing temperature and stocking density for large -scale artificial breeding of A. japonicus’s larvae. 相似文献
20.
Effect of temperature and irradiance on growth and reproduction of Enteromorpha prolifera that bloomed offshore along the Qingdao coast in summer 2008, was studied. It was showed that E. prolifera propagated mainly asexually with specific growth rate （SGR） of 10.47 at 25℃/40 μmol m^-2s^-1. Under this condition, gametes with two flagellate formed and released in 5 days. At the beginning of the development, the unicell gamete divided into two cells with heteropolarity, and then the apical cell developed into thalli primordial cells, whereas the basal cell developed into rhizoid primordial cells. In 8-day culture, the monoplast gamete developed into juvenile germling of 240 μm in length. Unreleased gametes can develop directly within the alga body. E. prolifera could either reproduce through lateral branching or fragmenting except apomixis revealed by Microscopic observation. On aged tissue of E. prolifera, although the degraded pigments partially remained in faded algal filaments, numerous vegetative cells could still divide actively in the algal tissues. 相似文献