Electron-transparent Zone of Mycobacteria may be a Defence Mechanism

Nature ◽  
1970 ◽  
Vol 228 (5274) ◽  
pp. 860-861 ◽  
Author(s):  
P. DRAPER ◽  
R. J. W. REES
Keyword(s):  
Defence Mechanism ◽  
Transparent Zone

scholarly journals Brightly coloured tissues in limid bivalves chemically deter predators

2019 ◽  
Vol 6 (10) ◽  
pp. 191298
Author(s):  
Lindsey F. Dougherty ◽  
Alexandria K. Niebergall ◽  
Corey D. Broeckling ◽  
Kevin L. Schauer ◽  
Jingchun Li
Keyword(s):  
Mass Spectrometry ◽  
Chemical Defence ◽  
Chemical Compositions ◽  
Marine Bivalve ◽  
Metabolomic Analysis ◽  
Defence Mechanism ◽  
Defensive Compounds ◽  
Mantis Shrimp ◽  
Metabolite Profiles ◽  
Bivalve Tissues

Members of the marine bivalve family Limidae are known for their bright appearance. In this study, their colourful tissues were examined as a defence mechanism towards predators. We showed that when attacked by the peacock mantis shrimp ( Odontodactylus scyllarus ), the ‘disco’ clam, Ctenoides ales , opened wide to expose brightly coloured tissues to the predator. The predator also significantly preferred to consume the internal, non-colourful clam tissues than the external, colourful tissues. Mass spectrometry-based metabolomic analysis confirmed that colourful tissues had significantly different chemical compositions than the non-colourful ones. The internal, non-colourful tissues had metabolite profiles more similar to an outgroup bivalve than to the species' own colourful external tissues. A number of the compounds that differentiated the colourful tissues from the non-colourful tissues appeared to be peptide-like, which potentially serve as the underlying defensive compounds. This is the first study demonstrating that colourful bivalve tissues are used for chemical defence.

What is the Evolutionary Advantage of Migraine?

Cephalalgia ◽  
2002 ◽  
Vol 22 (8) ◽  
pp. 624-632 ◽  
Author(s):  
E Loder
Keyword(s):  
Nervous System ◽  
Natural Selection ◽  
Environmental Factors ◽  
Genetic Factors ◽  
Evolutionary Perspective ◽  
Defence Mechanism ◽  
Design Constraint ◽  
Trade Off ◽  
Evolutionary Advantage ◽  
Evolutionary Explanations

Susceptibility to migraine is determined by genetic factors and is therefore subject to the forces of natural selection. Migraine is a common and ancient disorder whose prevalence may be increasing, suggesting that a migraine-prone nervous system may be associated with reproductive or survival advantages. Five evolutionary explanations are reviewed that might account for the persistence of migraine: (i) migraine as a defence mechanism; (ii) migraine as a result of conflict with other organisms; (iii) migraine as result of novel environmental factors; (iv) migraine as a trade-off between genetic harms and benefits; and (v) migraine as a design constraint. An evolutionary perspective on migraine allows the generation of important hypotheses about the disorder and suggests rewarding possibilities for further research.

Effects of Biological Response Modifiers with Different Modes of Action Used Separately and Together on Immune Responses in Mice with Syngeneic Tumours

1992 ◽  
Vol 20 (5) ◽  
pp. 406-421 ◽  
Author(s):  
K Matsunaga ◽  
I Morita ◽  
H Iijima ◽  
H Endoh ◽  
Y Oguchi ◽  
...  
Keyword(s):  
Immune Responses ◽  
Biological Response ◽  
Interferon Production ◽  
Defence Mechanism ◽  
Immunosuppressive Activity ◽  
Antitumour Effect ◽  
Bacille Calmette Guerin ◽  
Modes Of Action ◽  
Combined Use ◽  
Splenic Cells

The effect of a protein-bound polysaccharide (PSK) obtained from cultured mycelia of the Basidiomycetes Coriolus versicolor on activities involved in the host defence mechanism of C57BL/6 mice bearing adenocarcinoma 755 was compared with that of live bacille Calmette-Guérin (BCG). Delayed footpad reaction, the activity of splenic natural killer cells and interferon production induced by concanavalin A in splenic cells of healthy mice were little affected by PSK, but in mice bearing tumours PSK prevented the tumour-induced reduction in these activities. Live BCG augmented these activities in healthy mice but had little effect on the reduction of activities induced by a tumour. The immunosuppressive activity of the serum of tumour-bearing mice was reduced by PSK administration; live BCG did not have this effect. The combined use of live BCG and PSK improved these activities in the host, with synergistic increases in the antitumour effect. These results suggest that the combined use of live BCG and PSK, which have different modes of action, may be useful in the treatment of cancer.

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