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31.
Gabriela Trejo-Tapia Antonio Jiménez-Aparicio Luisa Villarreal Mario Rodríguez-Monroy 《Biotechnology letters》2001,23(23):1943-1946
Solanum chrysotrichum cell cultures were grown in a stirred tank bioreactor and their rheological and morphological behaviour were evaluated. The culture broths exhibited non-Newtonian and shear-thinning characteristics. Pseudoplasticity of the broths was governed by their biomass concentration. The roundness of aggregates measured as the elliptical form factor (EFF) had important changes. At the beginning of the culture the aggregates with an EFF lower than 2 represented 52% of the population, but in stationary phase the proportion increased to 77%. Whereas the size of aggregates did not change 80% of the population had an area lower than 0.1 mm2. Overall, these results indicate that the shape of the aggregate therefore needs to be considered when studying plant broth rheology. 相似文献
32.
Environmental change and predator diversity drive alpha and beta diversity in freshwater macro and microorganisms
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Pablo Augusto P. Antiqueira Owen L. Petchey Viviane Piccin dos Santos Valéria Maia de Oliveira Gustavo Quevedo Romero 《Global Change Biology》2018,24(8):3715-3728
Global biodiversity is eroding due to anthropogenic causes, such as climate change, habitat loss, and trophic simplification of biological communities. Most studies address only isolated causes within a single group of organisms; however, biological groups of different trophic levels may respond in particular ways to different environmental impacts. Our study used natural microcosms to investigate the predicted individual and interactive effects of warming, changes in top predator diversity, and habitat size on the alpha and beta diversity of macrofauna, microfauna, and bacteria. Alpha diversity (i.e., richness within each bromeliad) generally explained a larger proportion of the gamma diversity (partitioned in alpha and beta diversity). Overall, dissimilarity between communities occurred due to species turnover and not species loss (nestedness). Nevertheless, the three biological groups responded differently to each environmental stressor. Microfauna were the most sensitive group, with alpha and beta diversity being affected by environmental changes (warming and habitat size) and trophic structure (diversity of top predators). Macrofauna alpha and beta diversity was sensitive to changes in predator diversity and habitat size, but not warming. In contrast, the bacterial community was not influenced by the treatments. The community of each biological group was not mutually concordant with the environmental and trophic changes. Our results demonstrate that distinct anthropogenic impacts differentially affect the components of macro and microorganism diversity through direct and indirect effects (i.e., bottom‐up and top‐down effects). Therefore, a multitrophic and multispecies approach is necessary to assess the effects of different anthropogenic impacts on biodiversity. 相似文献
33.
Egg size and emergence timing affect morphology and behavior in juvenile Chinook Salmon,Oncorhynchus tshawytscha
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Karen M. Cogliati Julia R. Unrein Heather A. Stewart Carl B. Schreck David L. G. Noakes 《Ecology and evolution》2018,8(1):778-789
Variation in early life history traits often leads to differentially expressed morphological and behavioral phenotypes. We investigated whether variation in egg size and emergence timing influence subsequent morphology associated with migration timing in juvenile spring Chinook Salmon, Oncorhynchus tshawytscha. Based on evidence for a positive relationship between growth rate and migration timing, we predicted that fish from small eggs and fish that emerged earlier would have similar morphology to fall migrants, while fish from large eggs and individuals that emerged later would be more similar to older spring yearling migrants. We sorted eyed embryos within females into two size categories: small and large. We collected early and late‐emerging juveniles from each egg size category. We used landmark‐based geometric morphometrics and found that egg size appears to drive morphological differences. Egg size shows evidence for an absolute rather than relative effect on body morphology. Fish from small eggs were morphologically more similar to fall migrants, while fish from large eggs were morphologically more similar to older spring yearling migrants. Previous research has shown that the body morphology of fish that prefer the surface or bottom location in a tank soon after emergence also correlates with the morphological variations between wild fall and spring migrants, respectively. We found that late‐emerging fish spent more time near the surface. Our study shows that subtle differences in early life history characteristics may correlate with a diversity of future phenotypes. 相似文献
34.
Previous studies have shown that chronic administration of SR-3 (a 1:4 mixture of -linolenic and linoleic acid) affects spatial learning, thermoregulation, pain threshold and protection from seizures. The mode of action is unknown. One possible explanation is that the preparation induces changes in the fatty acids profile and in the cholesterol level in the neuronal membrane. This study used 15 independent groups of rats (n = 12) which were given either saline, mineral oil (vehicle) or SR-3 (25 mg/kg) for 0, 1,2, 3, or 4 weeks. The learning performance was measured in the Morris Water tank and the fatty acids profile and the cholesterol level were examined by the GC method in synaptosomes obtained from the frontal cortex of the rats. SR-3 improved the learning performance and induced major changes in the neuronal membrane composition, such as an increase in the total level of fatty acids, an increase in the level of essential fatty acids and a decrease in the cholesterol level. Those changes occurred after 3 weeks of treatment. The biochemical variables can predict the behavioral variables but not vice versa. The changes in the neuronal membrane may result in a modification of the membrane fluidity, which may, in turn, enhance cognitive and neuropharmacological effects. 相似文献
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37.
K.-T. Lee T. Suzuki T. Yamakawa T. Kodama Y. Igarashi K. Shimomura 《Plant cell reports》1999,18(7-8):567-571
A scale up of transformed root cultures of Atropa belladonna from a 300-ml flask to a 30-l tank was accomplished without any reduction in alkaloid productivity. Cutting treatment of
seed cultures showed no distinct effect on root growth, morphology, and alkaloid content in conical flasks during 1 month
of culture. Randomly cut roots thus grown were further cultivated in 3-l and 30-l modified stirred bioreactors for a scale-up
culture. After 1 month of culture, 1490 mg of tropane alkaloids was produced by a 30-l culture of A. belladonna transformed roots. These roots contained the same level of atropine (5.4 mg/ g dw) as the roots of this plant grown in the
field for 12 months and still contained a considerable amount of other alkaloids including 1.6 mg/g dw of 6-β-hydroxyhyoscyamine, 0.9 mg/g dw of scopolamine, and 2.0 mg/g dw of littorine.
Received: 12 June 1998 / Revision received: 31 August 1998 / Accepted: 27 October 1998 相似文献
38.
Toshihiko Kimura Masataka Watanabe Kunio Kohata Ryuichi Sudo 《Journal of applied phycology》1999,11(3):301-311
The ecological advantage of diel vertical migration on the nutrition and accumulation of Chattonella antiqua, which is one
of the dominant red-tide forming phytoplankton species in the Seto Inland Sea of Japan, was examined using a large axenic
culture tank, in which vertical stratification of salinity, temperature and nutrients was maintained, analogous to natural
conditions observed when red tides occur. C. antiqua was capable of migrating through very sharp salinity and temperature
gradients. At night the species migrated to the deep nutrient-rich water and assimilated nutrients. During the daytime it
migrated to the nutrient-depleted surface water and used the accumulated nutrients for photosynthesis. Nitrogen uptake was
synchronized with phosphate uptake. 31P-NMR spectroscopy during the migration experiment revealed that C. antiqua has the capability of nocturnal phosphate uptake
in the deep nutrient-rich water, but no capability of synthesizing polyphosphate, which was considered to be the intracellular
phosphate pool. These findings were compared with those reported for another raphidophycean, Heterosigma akashiwo. Although
both species carry out vertical migration and nocturnal nutrient uptake, only H. akashiwo has the capability of making an
intracellular polyphosphate pool.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
39.
40.
The effect of environmental colour on the growth,metabolism, physiology and skin pigmentation of the carnivorous freshwater catfish Lophiosilurus alexandri
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D. C. Costa C. C. Mattioli W. S. Silva R. Takata F. O. P. Leme A. L. Oliveira R. K. Luz 《Journal of fish biology》2017,90(3):922-935
The growth, physiology and skin pigmentation of pacamã Lophiosilurus alexandri juveniles were evaluated in an experiment using different tank colours (white, yellow, green, blue, brown and black) over an 80 day period. The tank colours did not cause significant differences to final body mass, total length, survival rate, carcass composition (moisture, crude protein, ash, ether extract, calcium, phosphorus, energy), or to plasma protein, triglyceride and cholesterol values. Haematocrit values, however, were highest for fish kept in white tanks (ANOVA P < 0·05), while the greatest haemoglobin levels were recorded for fish kept in blue and brown tanks (P < 0·01). The concentrations of cortisol (P < 0·001) and glucose (P < 0·01) were the most in fish in the black tanks. Tank colour affected skin pigmentation significantly, with fish in white tanks having the highest values of L* (brightness) and the lowest values in blue and black tanks. L*, however, decreased in all treatments throughout the experiment. C*ab increased significantly over the course of the experiment in fish kept in white tanks. Similar increases of C*ab were recorded in the other treatments but to a lesser extent. The use of black tanks during the cultivation of L. alexandri caused stress and should be avoided. Cultivation in white and yellow tanks produced individuals with a pale skin colour, while cultivation in blue and black tanks resulted in juveniles with a darker and more pigmented skin. 相似文献