Ecology and behavior ofPresbytis thomasi in Northern Sumatra

A field study of 23 bisexual troops, ranging in size from 3 to 21 members ( =8), and two all-male groups of the Thomas's leaf monkey (Presbytis thomasi) was conducted in North Sumatra from November 1981 to April 1984. Most troops (N=19 or 82.6%) contained only one adult male. Two troops and one group were most intensively studied. The home range was 12.3–15.7 ha for the two bisexual troops, and only 1.7 ha for the one, all-male, ten-member group. Fruits composed more than 50% of their diets. Vocalizations were classified into 13 types. Births occurred at any time of the year. Among three males of a bisexual troop, serious fights were observed: two males died of wounds and the former beta male became the new alpha male. After this social change, the home range area of this troop gradually shifted eastward. But, 3.5 months after the social change, a 9-month-old infant male stayed alone in the western part of its former range. Thereafter, he became a solitary male and sometimes went into the riverine area of the Bohorok river. The occurrence of male replacement suggests instability of multi-male organization in bisexual troops. Moreover, the different mortality rate between males and females and the unequal sex ratios forced by the formation of one-male troops, maintained high tension levels among males competing on females.     

Delayed fluorescence imaging of photosynthesis inhibitor and heavy metal induced stress in potato

Early chemical-induced stress in Solanum tuberosum leaves was visualized using delayed fluorescence (DF) imaging. The ability to detect spatially heterogeneous responses of plant leaves exposed to several toxicants using delayed fluorescence was compared to prompt fluorescence (PF) imaging and the standard maximum fluorescence yield of PSII measurements (Fv/Fm). The toxicants used in the study were two photosynthesis inhibitors (herbicides), 100 μM methyl viologen (MV) and 140 μM diuron (DCMU), and two heavy metals, 100 μM cadmium and 100 μM copper. The exposure times were 5 and 72 h. Significant photosynthesis-inhibitor effects were already visualized after 5 h. In addition, a significant reduction in the DF/PF index was measured in DCMU- and MV-treated leaves after 5 h. In contrast, only DCMU-treated leaves exhibited a significant decrease in Fv/Fm after 5 h. All treatments resulted in a significant decrease in the DF/PF parameter after 72 h of exposure, when only MV and Cd treatment resulted in visible symptoms. Our study highlights the power of delayed fluorescence imaging. Abundant quantifiable spatial information was obtained with the instrumental setup. Delayed fluorescence imaging has been confirmed as a very responsive and useful technique for detecting stress induced by photosynthesis inhibitors or heavy metals.