Characterization of the immune response to collagen-like proteins Scl1 and Scl2 of serotype M1 and M28 group A Streptococcus

Group A Streptococcus (GAS) infections may trigger autoimmune sequelae thought to involve streptococcal antibodies cross-reactive to human antigens. Here, the antigenicity of the streptococcal collagen-like (CL) proteins, Scl1 and Scl2, that exhibit structural similarity to human collagen, was analyzed. Antibodies to Scl1.1 protein were detected in human sera from healthy individuals previously infected with M1 GAS and from patients with various GAS infections, as well as in sera from mice infected with M1 GAS. Linear B-cell epitope mapping identified immunoreactive peptides corresponding to the CL region of Scl1.1. Humoral responses to Scl1.28 and Scl2.28 were also detected in pediatric patients and mice infected with M28 GAS.     

A new method for wide frequency range dynamic olfactory stimulation and characterization

Sensory receptors often receive strongly dynamic, or time varying, inputs in their natural environments. Characterizing their dynamic properties requires control and measurement of the stimulus over a frequency range that equals or exceeds the receptor response. Techniques for dynamic stimulation of olfactory receptors have lagged behind other major sensory modalities because of difficulties in controlling and measuring the concentration of odorants at the receptor. We present a new method for delivering olfactory stimulation that gives linear, low-noise, wide frequency range control of odorant concentration. A servo-controlled moving bead of silicone elastomer occludes the tip of a Pasteur pipette that releases odorant plus tracer gas into a flow tube. Tracer gas serves as a surrogate indicator of odorant concentration and is measured by a photoionization detector. The system has well-defined time-dependent behavior (frequency response and impulse response functions) and gives predictable control of odorant over a significant volume surrounding the animal. The frequency range of the system is about 0-100 Hz. System characterization was based on random (white noise) stimulation, which allows more rapid and accurate estimation of dynamic behavior than deterministic signals such as sinusoids or step functions. Frequency response functions of Drosophila electroantennograms stimulated by fruit odors were used to demonstrate a typical application of the system.     

Dose-dependent nonassociative olfactory learning in a fly

Olfactory sensory stimulation induces a fast-phase arrest response (FPA-R) of the blowfly heart activity that has been described as a sensitive tool for testing insect reactivity to odor perception. We analyzed FPA-R occurrence to repeated olfactory stimulation with low and high 1-hexanol concentrations that are behaviorally attractant and repellent, respectively, in the blowfly. FPA-R occurrence diminished and ceased with repeated presentations of low and medium odor concentrations, according to dynamics inversely related to odor doses. On the other hand, repeated stimulation with higher odor concentrations induced persistent FPA-Rs. Sensory input amplitude to repeated presentations of singly tested odor concentrations did not change throughout stimulation sessions. A spontaneous restoration of FPA-R to olfactory stimulation was recorded 30 min after cessation of FPA-R to a previous olfactory stimulation session. However, a prompt restoration of FPA-R to olfactory stimulation after cessation of FPA-R was obtained following mechano-taste stimulation of labellar sensilla. Our findings show that the FPA-R habituates to olfactory sensory stimulation with low and medium odor concentrations according to dynamics inversely related to odor intensities. On the other hand, the FPA-R does not habituate to higher odor concentrations. Therefore, flies learn to disregard nonaversive odor information, but they cannot ignore iterative detection of a repellent volatile.     

松墨天牛对马尾松挥发物的触角电位和行为反应

利用触角电位和嗅觉测定技术,比较分析松墨天牛Monochamus alternatus Hope对马尾松(Pinus massoniana Lamb)健康和松材线虫危害的枝条挥发物的触角电位和行为反应特点。实验结果表明:未交配松墨天牛对健康枝条挥发物的EAG反应值大于被害枝条的,交配后天牛对被害枝条的EAG反应值明显大于健康枝条的。在“Y”型嗅觉仪中,未交配天牛对健康枝条挥发物表现为正趋性,对被害枝条挥发物表现为负趋性,而交配后天牛对被害枝条挥发物表现为正趋性,对健康枝条挥发物表现为负趋性。说明不同发育时期的松墨天牛成虫对不同生理状态的寄主具有不同的敏感性和选择性。     

Cell envelope changes in Bifidobacterium animalis ssp. lactis as a response to bile

Bifidobacterium animalis ssp. lactis is a probiotic frequently used as adjunct culture in fermented dairy products. In order to ensure its proper function at the intestinal level, this bacterium has to be tolerant to physiological concentrations of bile. This study examined the influence of bile on the fatty acid composition and the membrane characteristics of B. animalis IPLA 4549 and its mutant with acquired resistance to bile, B. animalis 4549dOx. Bile adaptation triggers in B. animalis 4549dOx a decrease in membrane fluidity and in the protein : phospholipid ratio, as well as a shift in the fatty acid composition of the cell. Remarkably, the presence of bile in the growth medium induced similar changes in both B. animalis cells. Furthermore, transmission electron microscopy analysis showed that bile promotes a severe distortion of the cell surface. This study provides new insights of the action of bile on the cell envelope of bifidobacteria.     

微小花蝽对温室白粉虱的捕食作用

研究微小花蝽Orius minutus(L.)对温室白粉虱Trialeurodes vaporariorum(Westwood)的捕食作用。结果表明,微小花蝽成虫对温室白粉虱各虫态的功能反应呈HollingⅡ型。微小花蝽成虫对温室白粉虱卵、1龄和2龄混合若虫及其3龄若虫的理论最大捕食量分别为123,74和52头/d。微小花蝽成虫对温室白粉虱卵的捕食效应随捕食者个体间干扰作用的增加而下降,符合Hassel-Varley方程,捕食作用率(E)随着微小花蝽数(P)增加而呈幂指数下降,模拟模型E=0.1021P-0.3189,干扰系数为0.3189。在15～40℃的温度范围内,随着温度的升高微小花蝽成虫对温室白粉虱卵的寻找效率提高,最高达1.1990,处置时间缩短,最低达到0.0035d。     

Behavioral and physiologic responses to environmental enrichment in the maned wolf (Chrysocyon brachyurus)

The ex situ population of maned wolves is not self‐sustaining due to poor reproduction, caused primarily by parental incompetence. Studies have shown that environmental enrichment can promote natural parental behaviors in zoo animals. The objective of this study was to determine the effects of environmental enrichment on behavioral and physiological responses of maned wolves. During an 8‐week experimental period, daily behavior observations and fecal sample collection were conducted on four adult wolves (2.2) individually housed in environments without enrichment. After 2 weeks, the wolves were chronologically provided with 2‐week intervals of hiding dead mice around the exhibit, no enrichment, and introduction of boomer balls. Responses of the wolves to enrichment were assessed based on activity levels and exploratory rates, as well as the level of corticoid metabolites in fecal samples collected daily throughout the study period. Providing wolves with environmental enrichment significantly increased exploratory behaviors (P<0.05), especially when mice were hidden in the enclosure. Fecal corticoid concentrations were increased during periods of enrichment in males (P<0.05), but not in females. Overall, there were no correlations between behavioral responses to enrichment and fecal corticoid levels. Behavioral results suggest that environmental enrichment elicits positive effects on the behavior of captive maned wolves. There is evidence suggesting that providing animals with ability to forage for food is a more effective enrichment strategy than introducing objects. There is need for a longer term study to determine the impact of environmental enrichment in this species. Zoo Biol 26:331–343, 2007. © 2007 Wiley‐Liss, Inc.