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Despite its obvious costs, autotomy of a body part is a common and effective behavioral strategy to avoid predation. For several species, this limb loss may impact the ability to escape future predation events. Lizards that lose tails are slower to climb or run, and crickets that autotomize legs can jump less far. Epibenthic brittle stars frequently autotomize arms but the effect of arm loss on their escape speed has not been examined. Using two species, spiny (Ophiocoma echinata) and banded-arm (Ophioderma appressum) brittle stars, we predicted that brittle stars missing an arm would move more slowly than intact individuals. Individual brittle stars, either intact or with one arm cut off, were placed in the center of a sandy, well-lit, subtidal arena and allowed to move under the rocks surrounding the arena. We found a positive relationship between the size of the brittle star and its speed. However, there was no difference between escape speeds of intact brittle stars and ones missing an arm for either species. Our data suggest that autotomy has little impact on speed. Thus, unlike many other species, autotomy of an arm does not appear to negatively impact the ability of brittle stars to escape future predation events.
Plants respond to damage by herbivores with a variety of resistance characters including trichome production and the production of secondary compounds. These induced responses play important roles in species interactions, often protecting plants from herbivorous insects or pathogens, and there is growing interest in applying such information to solving pest problems in agriculture with the potential for using endogenous chemical elicitors instead of pesticides promising the development of more environmentally sustainable agricultural practices. The objective of this study is to investigate the extent to which trichomes are induced by the same stimuli shown to induce chemical responses in plants. Using the cultivated tomato (Solanum lycopersicum var. esculentum), the number of trichomes produced on leaves was compared after the application of the following treatments: simulated herbivory, natural herbivory, and jasmonic acid (JA) spray. Twenty-five plants were grown, and five randomly assigned to each treatment. Plants were grown in a greenhouse in a randomized block design to control for spatial effects. Treatments were applied after two true leaves had fully developed. Samples were collected from the terminal leaflet of the fifth true leaf, tissue examined using scanning electron microscopy, and the number of different types of trichomes on each sample was quantified. Our results showed significantly higher trichome production on the terminal leaflet of the fifth leaf of plants treated with herbivory and JA compared to control plants and plants treated with mechanical damage. Natural herbivory and JA induced nearly twice as many trichomes as compared to the control plants. There was also a trend showing an increase in glandular trichome Type VI in response to herbivory and JA, although the effect of treatment on trichome type was not statistically significant.
Host immune factors involved in bacterial ocular virulence were examined through the use of pneumolysin, a cytoplasmic protein and pneumococcal strain D39 utilizing human corneal epithelial cells (HCEC). Recombinant pneumolysin activity was determined by a hemolysis assay using the following concentrations: 50-1000 ng/mL. HCEC were grown to confluency and exposed to 103 to 107 colony forming units (CFUs) of mid-log phase Streptococcus pneumoniae D39 for 2, 4, 6, and 24 h. HCEC were exposed to pneumolysin at various concentrations: 200-1000 ng/mL. ELISA and human cytokine array was performed on the supernatant. Fluorescence studies using cytotoxicity assay were performed on the HCEC cells following infection to determine live versus dead cells. The hemolysis assay showed that a minimum of 100 ng/mL PLY will lyse the red blood cells. Cytokine array on the HCEC exposed supernatants showed the presence of IL-6 and IL-8. Four hour exposure of HCEC cells to a range of 103 to 107 CFU of D39 resulted in monolayer disruption and decreased viability as compared to cells exposed to the media alone. HCEC cells exposed to any of the concentrations of bacteria exhibited signs of cellular damage and death. Following 24 h exposure, there was an increased expression of IL-8 (p < 0.001) compared to media alone. IL-6, IL-8 and IFN-gamma levels were elicited at a minimal of 200ng PLY. In addition to changes in viability and morphology of cultured cells, we detected specific cytokines in the culture supernatants of HCEC following exposure to S. pneumoniae D39.
Circadian rhythms are 24 hour cycles of physiology and behavior that evolved for adaptation to changes in environment and physiological state. We hypothesize circadian rhythms adjust to metabolic demands of lactation. Our objective was to determine if circadian rhythms of behavior, body temperature, cortisol and melatonin were different between ewes suckling twins and singletons after two weeks of lactation. Two groups of ewes (n = 5 ewes/group) suckling singleton or twin lambs were acclimated to sampling protocol for 5 d beginning 7 ± 1 d postpartum. After acclimation, behavior was measured (i.e. suckling, eating, drinking, lying down) every 10 min over 24 h. During the following 24 h period, milk, saliva, and rectal temperature were collected every 4 h. Salivary cortisol and melatonin levels were measured with ELISA. Singleton (4.1 ± 1.1 kg) and twin (5.2 ± 1.2 kg) lamb weight and ewe body condition score (BCS: 2.8 ± 0.2 and 2.7 ± 0.2, respectively) were not different (p > 0.05) at birth. At 9-12 d postpartum singleton (9.5 ± 2.6 kg) and twin (8.2 ± 1.5 kg) lamb weight and ewe BCS (2.9 ± 0.2 and 2.8 ± 0.2, respectively) were not different. However, total offspring weight per dam was greater in twin (15.5 ± 2.3 kg) than singleton (9.5 ± 2.6 kg; p < 0.05) group. Average daily gain for individual twins was roughly half of singleton, and net daily weight gain was not different, suggesting metabolic demand on ewes suckling twins was not significantly different from ewes suckling singletons. Lack of difference in suckling behavior score was consistent with lack of difference in metabolic demand between the groups of ewes. Salivary cortisol levels, melatonin levels, and rectal temperature measurements were not significantly different between groups. Circadian rhythms of standing, lying and eating behaviors were similar among groups. Ewes in the twin group ate more frequently during light phase suggesting that slightly higher metabolic demand of suckling twins may be met by increasing consumption alone in the first 2 weeks of lactation.
Despite the increased incidence of fibrotic diseases with advancing age, little is known about the role of aging in these pathologies. Recent studies have proposed that senescence is an anti-fibrotic mechanism that promotes fibrosis resolution through apoptotic clearance of senescent cells. However, all of these studies were performed using young mice. It is not known whether the fate of senescent cells is altered in the context of aging. Here, lung myofibroblasts were isolated from young (2 month) and aged (20 month) mice, and cells were cultured ex vivo. Cells were treated with apoptotic stimuli and cellular viability was assessed. Senescent myofibroblasts exhibited increased resistance to cell death as compared to myofibroblasts isolated from young mice. Secreted factors from young myofibroblasts restored susceptibility of senescent myofibroblasts to cell death. These findings challenge the concept of cellular senescence as an anti-fibrotic mechanism and offer proof-of-concept that the fate of senescent cells may be altered in the context of aging. These studies provide insight into therapeutic treatment strategies for pathological fibrosis associated with aging.