Emasculation: gloves-off strategy enhances eunuch spider endurance.

Males of sexually cannibalistic spiders commonly mutilate parts of their paired genitals (palps) during copulation, which may result in complete emasculation or the 'eunuch phenomenon'. In an orb-web nephilid spider, Nephilengys malabarensis, about 75 per cent of males fall victim to sexual cannibalism, and the surviving males become half-eunuchs (one palp emasculated) or full-eunuchs (both palps emasculated). While it has been shown that surviving eunuchs are better fighters compared with intact males when guarding the females with which they have mated, mechanisms behind eunuchs' superior fighting abilities are unknown. The previously proposed 'gloves-off' hypothesis, attributing eunuchs' enhanced locomotor endurance to the reduction in total body weight caused by genital mutilation, is plausible but has remained untested. Here, we tested the gloves-off hypothesis in N. malabarensis by comparing the time until exhaustion (i.e. endurance) of intact males with half- and full-eunuchs created experimentally. We found that by reducing body weight up to 4 per cent in half-eunuchs and 9 per cent in full-eunuchs through emasculation, endurance increases significantly in half-eunuchs (32%) and particularly strongly in full-eunuchs (80%). Our results corroborate the gloves-off hypothesis and further point towards the adaptive significance of male emasculation.

Progression of periodontal destruction and the roles of advanced glycation end products in experimental diabetes.

BACKGROUND: Progression of diabetes-associated periodontal destruction and the roles of advanced glycation end products (AGEs) are investigated. METHODS: Diabetes was induced by streptozocotin injection, and periodontitis was induced via silk ligature placement with Porphyromonas gingivalis lipopolysaccharide injection in 64 Sprague-Dawley rats for 7 to 21 days. The quality of alveolar bone and attachment loss (AL) were measured by microcomputed tomography and histology. Destruction profiles were evaluated by histology, histochemistry, immunohistochemistry, and quantitative assessments of inflammatory cells, expression of receptors for AGEs (RAGE), tartrate-resistant acid phosphatase, and proliferating cell nuclear antigen. RESULTS: Without periodontitis induction, there was no obvious morphologic change in the periodontium, although slight elevations of AGEs and RAGE levels were noted in animals with diabetes. In the group with experimental periodontitis, significant periodontal bone loss was noted in animals both with and without diabetes from day 7, with more progressive bone loss in animals with diabetes during days 14 to 21. Histologically, the disruption of attachment and inflammation were observed from day 7, but subsequently subsided in animals without diabetes. A stronger and more prolonged response with significant AL was observed in animals with diabetes. Stronger inflammation, attenuated and persistent resorptive activity, and weaker proliferating potential were demonstrated by animals with diabetes. AGE deposition and RAGE expression were noted in animals without diabetes but with periodontitis, although levels were considerably elevated in the later stages in animals with diabetes. CONCLUSIONS: Diabetes augments periodontal destruction by reducing the proliferating capability and activating resorptive activities. Presence of the AGE-RAGE axis without diabetes implies that it is involved in the regulation of inflammation.