植物乳杆菌CCFM8724抑制双菌生物膜的成分初探

【背景】植物乳杆菌是一种重要的益生菌,本实验室前期研究表明植物乳杆菌CCFM8724发酵液可抑制变异链球菌和白色念珠菌双菌生物膜,但植物乳杆菌发酵液中起作用的具体物质尚不清楚。【目的】评价植物乳杆菌CCFM8724发酵液抑菌成分的特性,初步探究其物质基础。【方法】探索温度、pH等因素对抑菌物质的影响,采用气相色谱-质谱(Gas Chromatography-Mass Spectrometry,GC-MS)联用技术分析植物乳杆菌代谢物的组成,进一步通过有机溶剂萃取、超滤等方法初步分离纯化发酵液中抑制双菌生物膜的成分,并采用液相色谱-质谱(Liquid Chromatography-Mass Spectrometry,LC-MS)联用技术进行鉴定。【结果】通过多元统计分析,发现植物乳杆菌发酵液的主要差异标志物为有机酸(如苯乳酸、乙酸、羟基己酸和甘油酸等),经过初步提取鉴定并进行功能验证,其中有效成分主要为有机酸和环肽类化合物。【结论】植物乳杆菌CCFM8724发酵液主要通过多种有机酸和环肽类的协同作用抑制变异链球菌和白色念珠菌生物膜,该研究为植物乳杆菌发酵液进一步的分离纯化和有效成分的生产...     

Proteomic analysis of gamma-butyrolactone-treated mouse thalamus reveals dysregulated proteins upon absence seizure

Absence seizure has been of interest because the symptom is related to sensory processing. However, the mechanism that causes the disease is not understood yet. To better understand the molecular mechanism related to the disease progress at protein level, we performed proteomic studies using the thalamus of mice for which absence seizure was induced by gamma-butyrolactone (GBL). Differential proteome expression between GBL-treated mice and control mice was examined by fluorescence 2D difference gel electrophoresis (DIGE) at three different time points (5, 10, and 30 min) after GBL-administration. We identified 16 proteins differentially expressed by >1.4-fold at any of the three time points. All proteins besides the serine protease inhibitor EIA were down-regulated in absence seizure-induced mice. The down-regulated proteins can be classified into five groups by their biological functions: cytoskeleton rearrangement, neuroprotection, neurotransmitter secretion, calcium binding, and metabolism. The maximum level of change was reached by 10 min after GBL-treatment, with the expression level returning back to the original at 30 min when mice were awakened from absence seizure thereby demonstrating the proteomic response is reversible. Our results suggest that absence seizures are associated with restricted functional sets of proteins, whose down-regulation may interfere with general function of neuronal cells.     

Chemostimuli implicated in selection of oviposition substrates by the stable fly Stomoxys calcitrans

Horse and cow dung were tested as substrates for oviposition by the stable fly Stomoxys calcitrans (L) (Diptera: Muscidae) in laboratory cages. Odour alone from either horse or cow dung was sufficient to attract flies for oviposition. This was confirmed in wind tunnel experiments, where both horse and cow dung were shown to attract gravid stable flies. However, when S. calcitrans was offered a choice between these two oviposition substrates, flies always chose horse dung over cow dung, both when allowed to contact the substrates and when relying on dung odour alone. Analyses of volatile compounds emanating from horse and cow dung by gas chromatography linked antennogram recordings from S. calcitrans antennae revealed no differences in the chemostimuli released from the two substrates. The predominant chemostimulant compounds in both substrates were carboxylic acids (butanoic acid), alcohols (oct-1-en-3-ol), aldehydes (decanal), ketones (octan-3-one), phenols (p-cresol), indoles (skatole), terpenes (beta-caryophyllene) and sulphides (dimethyl trisulphide). Higher levels (20-40 p.p.m.) of carbon dioxide were recorded over horse dung compared with cow dung, a factor that may contribute to the preference exhibited by S. calcitrans for this substrate for oviposition.     

Reduced expression of INK4a/ARF genes in stem-like sphere cells from rat sarcomas

The presence of cancer stem cells, in both hematopoietic and solid malignancies, has been recently linked to their pathogenesis. We aimed to identify the characteristics and stem-like properties of sphere-colony forming cells in rat osteosarcoma and malignant fibrous histiocytoma cell lines. The results showed that both cell lines possessed an ability to form spherical, clonally expanding colonies in anchorage-independent, serum-starved conditions in N2/1% methylcellulose medium. The sphere cells showed stem-like properties with the ability to self-renew, and expressed the stem cell-related STAT3 and Bmi1 genes. Interestingly, spheres from both sarcomas remarkably decreased the expression of INK4a/ARF locus genes, p16(INK4a) and p19(ARF), which could be related to the resistance against cell senescence and apoptosis. Spheres showed strong tumorigenicity with metastatic potential in vivo via the inoculation into syngeneic rats, suggesting the presence of these populations might contribute to the tumor development such as metastasis via the resistance to apoptotic stimuli.     

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.     

Food perception with age and its relationship to pleasantness

Differences between elderly subjects (n = 46, 61-86 years) and young subjects (n = 36, 18-25 years) in food perception and food liking were investigated. Intensity and liking ratings were assessed for custard dessert, in which flavor enrichment, textural change, and irritant addition were incorporated as strategies to compensate for sensory losses with increasing age. The sensory acuity (taste, olfaction, irritation, chewing efficiency) of both young and elderly subjects was measured with the help of different sensitivity tests. The elderly perceived the custards differently from the young, mainly as less intense in flavor (cherry/vanilla) and less intense in creaminess/swallowing effort. Several of the observed interaction effects were different for the elderly and the young. The majority of these differences manifested as lower intensity slopes for the elderly. Losses in sensitivity to taste and to olfactory and trigeminal stimuli as well as a reduced chewing efficiency were observed on average for the elderly compared with the young. Furthermore, subgroups of the elderly were observed in which the compensatory strategies flavor enrichment, textural change, and irritant addition led to an increase in food liking. However, these subgroups did not differ in their sensory acuity. The present study does not support the assumption that age-associated changes in food perception-caused by losses in sensory acuity-inevitably reduce the food liking of the elderly.     

Effects of Male Age and Cervical Proprioceptors on Sexual Aerial Pursuit by Male Flesh Flies, <Emphasis Type="Italic">Neobellieria bullata</Emphasis> (Diptera: Sarcophagidae)

Information from multiple sensory systems is likely combined to provide guidance for male muscoid flies engaged in aerial pursuit of females. To specify the female’s position to the thoracic flight motor, head-centered visual information should be integrated with propriosensory information about head position relative to the thorax because the flies’ heads are flexible around the neck. Head position is encoded by a proprioceptive organ in the ventral neck membrane. We determined in the flesh fly Neobellieria bullata (Sarcophagidae) that accurate propriosensory information is necessary for aerial capture of females by shaving mechanosensory hairs from the organ in male flies and competing them against their sham operated brothers in pursuits of virgin females. We also determined that normal male flies are not successful at capturing females until the second day post-eclosion.     

Crocodylus niloticus (Crocodilia) is highly sensitive to water surface waves

Crocodiles show oriented responses to water surface wave stimuli but up to now behavioral thresholds are missing. This study determines the behavioral thresholds of crocodilians to water surface waves. Nile crocodiles (Crocodylus niloticus) were conditioned to respond to single-frequency water surface wave stimuli (duration 1150 ms, frequency 15, 30, 40, 60 and 80 Hz), produced by blowing air onto the water surface. Our study shows that C. niloticus is highly sensitive to capillary water surface waves. Threshold values decreased with increasing frequency and ranged between 10.3 μm (15 Hz) and 0.5 μm (80 Hz) peak-to-peak wave amplitude. For the frequencies 15 Hz and 30 Hz the sensitivity of one spectacled caiman (Caiman crocodilus) to water surface waves was also tested. Threshold values were 12.8 μm (15 Hz) down to 1.76 μm (30 Hz), i.e. close to the threshold values of C. niloticus. The surface wave sensitivity of crocodiles is similar to the surface wave sensitivity of semi-aquatic insects and fishing spiders but does not match the sensitivity of surface-feeding fishes which is higher by one to two orders of magnitude.