The toxic effects of copper on larvae of the barnacle species Chthamalus challengeri

Two barnacle species (Semibalanus cariosus and Chthamalus challengeri) were studied during two years at Hokkaido, northern Japan, to find the interspecies boundary and to determine whether interspecific competition (interference and pre-emption) is important in maintaining the zonation in our study system. Both barnacle species showed tide level dependent distribution patterns in the boundary zone. Semibalanus cariosus was dominant at lower levels; this pattern was determined by post-recruitment mortality. This mortality pattern seemed to be set by physical stress because recruitment density and survival rate were not correlated with the cover of other species, and mortality was higher in higher zones where physical stress is more severe. Chthamalus challengeri was dominant at higher levels; this pattern was determined by recruitment. The recruitment density and survival rate of this species were not affected by the covers of other species, thus, neither interference nor pre-emption significantly affected the distribution pattern. Interspecific competition appears to be less important in organizing barnacle communities in our study area than in previously studied areas, however, the recruitment process is of major importance.

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Ultrastructure of the effect of T-514 obtained from Karwinskia humboldtiana on assembly and integrity of yeast's peroxisomes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084983 ◽

1991 ◽

Vol 49 ◽

pp. 136-137

Author(s):

J. Sepulveda-Saavedra ◽

I. Vander-Klei ◽

M. Venhuis ◽

Y. Piñeyro-Lopez

Keyword(s):

Culture Conditions ◽

Toxic Effects ◽

Candida Boidinii ◽

Central Mexico ◽

Poisonous Plant ◽

Biological Behaviour ◽

Enzyme Content ◽

Fat Deposits ◽

Yeast Model

Karwinskia humboldtiana is a poisonous plant that grows in semi desertic areas in north and central México. It produces several substances with different toxic effects. One of them designated T-514 damages severely the lung, kidney and liver, producing in the hepatoeyte large intracellular fat deposits and necrosis. Preliminary observations demonstrated that three is a decrease in the amount of peroxisomes in the hepatocytes of experimentally intoxicated rats and monkeys. To study the effect exerted by the T-514 on peroxisomes, a yeast model was selected, thus, three species: Saccha romices cerevisiae, Ilansenula polymorpha and Candida boidinii were used, because there is information concerning their peroxisome's morphology, enzyme content, biological behaviour under different culture conditions and biogenesis.

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Some Conditions Necessary for Pinocytosis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100457 ◽

1968 ◽

Vol 26 ◽

pp. 142-143

Author(s):

M. W. Brightman

Keyword(s):

Smooth Muscle ◽

Cell Membrane ◽

Toxic Effects ◽

Cytological Evidence ◽

Cell Processes

The cytological evidence for pinocytosis is the focal infolding of the cell membrane to form surface pits that eventually pinch off and move into the cytoplasm. This activity, which can be inhibited by oxidative and glycolytic poisons, is performed only by cell processes that are at least 300A wide. However, the interpretation of such toxic effects becomes equivocal if the membrane invaginations do not normally lead to the formation of migratory vesicles, as in some endothelia and in smooth muscle. The present study is an attempt to set forth some conditions under which pinocytosis, as distinct from the mere inclusion of material in surface invaginations, can take place.

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