The cytokines interleukin 1 (IL 1) and interferon (IFN) are immune response modifiers that are also pyrogenic and somnogenic. Tumor necrosis factor (TNF) (cachectin) is another pyrogenic monocyte product whose production can be elicited by somnogenic agents such as endotoxin. Human recombinant TNF (rTNF), therefore, was assayed for somnogenic activity. Intravenous (iv) or intracerebroventricular (ICV) injections of rTNF enhanced slow-wave sleep (SWS) and electroencephalographic slow-wave (0.5-4.0 Hz) activity. Recombinant TNF also suppressed rapid-eye-movement sleep (REM) and induced biphasic fevers whether given by intravenous or ICV injection. Responses to rTNF were compared with those elicited by human recombinant beta-IL 1 (rIL 1). Sleep responses elicited by rIL 1 were similar to those previously reported for native IL 1 and to those elicited by rTNF. However, unlike rTNF, rIL 1 induced monophasic fevers. Animal behavior and brain temperature changes that occur during the transition from one arousal state to another remained undisturbed after either rTNF or rIL 1 treatment. The fact that TNF and IL 1 as well as other immunoactive substances, e.g., IFN, muramyl peptides, and endotoxin, enhance SWS suggests that SWS is linked to the immune response. We conclude that TNF, in addition to IL 1 and IFN, is an endogenous somnogen.

We tested the hypothesis that if the quality or quantity of vegetation in small forest patches is greater than in large patches, then vegetation attributes may contribute to greater densities of white-footed mice (Peromyscus leucopus) in smaller patches. We trapped more mice per hectare in small (range 5–9 ha) than in large (range 110–150 ha) patches, as has been reported by other investigators. The difference appeared to be due primarily to the disproportionately high densities of P. leucopus in the edge habitat of small patches. While the greater edge-to-interior ratio in small patches could contribute to greater overall densities of mice in small patches, we trapped the same relative amount of edge and interior habitats in each of the six study patches. The structural complexity of understory vegetation was much greater in small than in large patches and also in edge than in interior habitats across the six patches. Thus, we trapped the most mice in the most structurally complex vegetation (i.e., edges of small patches). However, while vegetation at the edge of large patches was more complex than in the interior, we did not capture relatively high densities of P. leucopus in edge habitat of large patches. Hence, understory vegetation may differentially influence the distribution of P. leucopus between edge and interior habitats in forest patches of different sizes.

Exogenously administered tumor necrosis factor-alpha (TNF-alpha) elicits several symptoms of generalized infections such as fever, increased sleep, and anorexia. The aim of the present work was to localize these effects of TNF-alpha to specific amino acid sequences of the parent molecule by characterizing the in vivo and in vitro activities of several synthetic TNF-alpha fragments. Intracerebroventricular injection of TNF-alpha elicited dose-dependent fevers and increases in non-rapid-eye-movement sleep (NREMS) in rabbits. Four fragments also promoted NREMS and five elicited monophasic fevers. All of the somnogenic fragments share the amino acid sequence 31-36. In rats, TNF-alpha and one of the fragments [TNF-alpha-(69-100)] suppressed 12-h food intake. Furthermore, TNF-alpha increased the expression of the intercellular adhesion molecule-1 and enhanced interferon-gamma-induced HLA-DR expression in human glioblastoma cell line. In contrast, none of the fragments possessed these in vitro activities. Our in vivo results support the concept that there are biologically active regions in the TNF-alpha molecule.

Previously, it was suggested that a hypothalamic mechanism links somatotropin [growth hormone (GH)] secretion to sleep regulation, and this may explain the temporal correlation between GH release and nonrapid eye movement sleep (NREMS) on sleep onset. The purpose of these experiments was to study whether growth hormone-releasing factor (GRF), a hypothalamic peptide responsible for stimulation of GH secretion, also has the capacity to promote sleep in rats and rabbits. Artificial cerebrospinal fluid or GRF (human GRF-[1-40], 0.01, 0.1, and 1 nmol/kg) was intracerebroventricularly injected to rats at dark onset, and the electroencephalogram (EEG), brain temperature (Tbr), and motor activity were recorded for 24 h. Rabbits received the same doses of GRF during the light period, and sleep-wake activity was monitored for 6 h. GRF promoted NREMS and rapid eye movement sleep (REMS) and increased EEG slow-wave activity in both rats and rabbits. NREMS increased in postinjection hour 1 after low doses of GRF, whereas the effect was more prolonged after higher doses. REMS increased in response to the low and middle doses of GRF in postinjection hour 1 in rats and in hour 2 after each dose in rabbits. The diurnal rhythms of sleep-wake activity, motor activity, and Tbr were not affected in rats. Because GRF promotes sleep and also stimulates GH secretion, it is a likely candidate for linking GH secretion and sleep regulation.

Infection of injury results in several systemic and central reactions termed the acute phase response (APR). Substantial evidence suggests that cytokines induced by microbes initiate the APR. We compared the APR induced in rabbits by a model bacterial stimulus, lipopolysaccharide (LPS), to that induced by a model viral stimulus, polyriboinosinic:polyribocytidylic acid (poly I:C). The cytokine mRNA responses in a mouse macrophage cell line (RAW 264.7) to LPS or poly I:C were also determined. Rabbits were injected intravenously or intracerebroventricularly with different doses of LPS or poly I:C. Colonic temperatures (Tco) and blood samples were taken at the time of injection and at 3, 6, and 24 h after injection. Leukocyte numbers, serum antiviral activity, serum ceruloplasmin, and plasma fibrinogen were analyzed. Both intravenously injected LPS and poly I:C increased Tco, decreased leukocytes, and increased ceruloplasmin. Only LPS by the intravenous route increased fibrinogen, whereas only intravenously injected poly I:C induced antiviral activity. Intracerebroventricular injections of LPS and poly I:C also elicited dose-dependent febrile responses but did not change the hematologic APR significantly except for fibrinogen. The primary distinctions between LPS and poly I:C with respect to cytokine induction in the RAW 264.7 macrophage cell line were that LPS failed to induce interferon (IFN)-alpha, poly I:C induced interleukin (IL)-6 mRNA minimally and for a shorter time period than did LPS, and LPS induced IL-1 alpha and IFN-beta more rapidly than did poly I:C.(ABSTRACT TRUNCATED AT 250 WORDS)

Cannibalistic behaviour can be a limitation in mass rearing where predator-predator competition can be high. However, increasing habitat structural complexity has been shown to reduce cannibalism through a reduction in encounter rates and the provision of more refuge and oviposition sites. This study investigated the use of different rearing media and its ability to mitigate cannibalism in the predatory mite Amblydromalus limonicus (Garman & McGregor). The rearing substrates tested were buckwheat husks, gorse husks, rice husks, vermiculite, and wheat bran, which were compared against a control treatment with no substrate. These laboratory experiments were done in two different relative humidities (70% and 85%) with both water and pollen (Typha orientalis Presl) supplementation. The rearing media had a strong significant effect on populations of A. limonicus while humidity did not. Rice husk was found to hold the highest populations of the predator, whereas the control and wheat bran treatments had the lowest. The higher populations associated with the rice husk treatment were attributed to a decrease in encounter rates, the provision of additional shelter and oviposition sites, and low mould infestation. Issues with sampling bias, effects of mould in the system, and potential applications of rice husk are discussed.

Mutualistic symbionts are widespread in plants and may have strong, bottom-up influences on community structure. Here we show that a grass-endophyte mutualism shifts the composition of a generalist predator assemblage. In replicated, successional fields we manipulated endophyte infection by Neotyphodium coenophialum in a dominant, non-native plant (Lolium arundinaceum). We compared the magnitude of the endophyte effect with manipulations of thatch biomass, a habitat feature of known importance to spiders. The richness of both spider families and morphospecies was greater in the absence of the endophyte, although total spider abundance was not affected. Thatch removal reduced both spider abundance and richness, and endophyte and thatch effects were largely additive. Spider families differed in responses, with declines in Linyphiidae and Thomisidae due to the endophyte and declines in Lycosidae due to thatch removal. Results demonstrate that the community impacts of non-native plants can depend on plants' mutualistic associates, such as fungal endophytes.

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