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Evidence of climatic adaptation in spontaneous torpor among Pouched mice Saccostomus campestris from southern Africa

100%

Ellison G. T. H.

Acta Theriologica

1993

tom 38

nr 1

Spontaneous torpor was examined in 36 Pouched mice Soccosiomi/s campestris Peters, 1846 from 6 localities in southern Africa. Fifteen .individuals displayed characteristic bouts of torpor in which oxygen consumption (VO2) fell below 50% of the resting levels of non-torpid pouched mice for more than 2 hr during the early morning. These bouts ended in an abrupt increase in VO2 which oversfhot resting levels during arousal to normothermia. Minimum oxygen consumption (V02min) was not correlated with the energy saved during torpor, but there was a significant positive correlation between V02min and the duration of torpor (DO and also between Dt and energy saved. In contrast, there was a negative correlation between the cost of arousal and energy saved which suggests that the cost of regaining homeothermy can limit the energetic efficiency of short bouts of torpor. Pouched mice from all 6 localities had the capacity to enter torpor and there were no significant geographical differences in the incidence of torpor. However, there were substantial differences in the expression of torpor, and Pouched mice from localities experiencing more variable temperatures underwent significantly longer bouts of torpor which suggests that selection for torpor had been greater in more energetically unpredictable environments.

Resistance mechanisms of winter cereals and forage grasses to snow mould fungi

61%

Marzec K., Plazek A.

Zeszyty Problemowe Postępów Nauk Rolniczych

2008

tom 524

Winter survival of cereals and grasses depends mainly on plant resistance to low temperature and to snow mould fungi. To persist winter plants have to be tolerant to different kind of stresses: abiotic such as low temperature, long-term snow and ice cover, freeze-induced plant desiccation or frequent freezing and thawing, and biotic - many species of snow mould fungi. During the cold acclimation, cereals and grasses become more resistant to both stresses: cold and snow mould. Earlier seeded plants with a greater number of crowns are more resistant to snow mould. Infection caused by snow mould induces a complex plant response, including such processes as the synthesis of PR (pathogenesis-related) proteins (chitinase and β-1,3-glucanas), production of active oxygen species (AOS), synthesis of phenolics, phyotalexins, accumulation of callosis and soluble carbohydrates, and a decrease of water potential. In the paper the most common defence mechanisms against snow mould pathogens are discussed.

Ograniczanie wyników

1 Acta Theriologica

1 Zeszyty Problemowe Postępów Nauk Rolniczych

1 Ellison G. T. H.

1 Marzec K.

1 Plazek A.

1 2008

1 1993

Wyniki wyszukiwania

Evidence of climatic adaptation in spontaneous torpor among Pouched mice Saccostomus campestris from southern Africa

Resistance mechanisms of winter cereals and forage grasses to snow mould fungi