Preparation, purification and characteristics of an aflatoxin degradation enzyme from Myxococcus fulvus ANSM068

Aims: To prepare, purify and characterize an extracellular enzyme from Myxococcus fulvus ANSM068, designated as myxobacteria aflatoxin degradation enzyme (MADE), which possesses degradation activity against aflatoxin B₁ (AFB₁), G₁ (AFG₁) and M₁ (AFM₁) in solution. Methods and Results: The culture supernatant of strain M. fulvus demonstrated high degradation ability against AFB₁ (71·89%), AFG₁ (68·13%) and AFM₁ (63·82%) after 48 h of incubation. An enzyme was purified from the supernatant of M. fulvus using ethanol precipitation and chromatography on DEAE‐Sepharose and Superdex 75. An overall 166‐fold purification of the enzyme with a recovery of 57% and a final specific activity of 569·44 × 10³ U mg^?1 was obtained using the present purification protocol. The apparent molecular mass of MADE was estimated to be 32 kDa by SDS‐PAGE. AFG₁ and AFM₁ were significantly degraded, by 96·96 and 95·80%, respectively, when treated with pure MADE (100 U ml^?1) produced by strain ANSM068. MADE exhibited the largest amount of activity at 35°C and pH 6·0, with Mg²⁺ ions greatly promoting and Zn²⁺ strongly inhibiting MADE activity. Conclusions: An aflatoxin degradation enzyme from bacterial isolates can effectively remove aflatoxin B₁, G₁ and M₁ in solution. Significance and Impact of the Study: The high activity and wide temperature and pH range of MADE for the degradation of aflatoxin have promising applications in control of mycotoxins during food and feed processing.     

Hidden effects of high numbers of tourists in protected areas: displacement of foraging top scavengers

Protected areas in southern Europe are important for the conservation of large avian scavengers. However, the effects an increasing number of visitors may have on the scavengers' patterns of movement are unknown. Here, we took advantage of data collected from seven GPS-tagged adult Griffon Vultures Gyps fulvus breeding in the Bardenas Reales Natural Park in northern Spain to determine whether foraging birds moved to more remote areas on the days when the number of visitors increased. We found that although the number of visitors did appear to affect movement patterns, this had a smaller effect size compared with the mean temperature of the day. Additionally, males moved further than females. If the number of visitors to natural areas continues to increase, local exclusions of Griffon Vultures may become more common, so further research is needed to address the potential consequences for the scavenger population and ecosystem functions and services they provide.     

橙色粘球菌子实体形成过程的显微观察

利用体式显微镜(stereomicroscope,SMC)和扫描电镜(scanning electron microscope,SEM)对橙色粘球菌(Myxococcus fulvus)的子实体形成过程进行为期8 d的生长周期观察,揭示橙色粘球菌由营养体逐渐聚集变成子实体的过程;SMC观察得到粘细菌菌落形成聚集以及颜色逐渐变深,并最后形成突起的鲜亮的橙色球状子实体。SEM观察得到明显的群体细胞定向运动以及细胞堆积,粘细菌细胞由杆状营养体向球状粘孢子变化,并最终形成由粘孢子组成的球状子实体。     

Introduction of parasitoids has maintained a stable population of arrowhead scales at extremely low levels

We previously reported the drastic decline of the arrowhead scale, Unaspis yanonensis Kuwana (Hemiptera: Diaspididae) following the introduction of two parasitoid species, Aphytis yanonensis DeBach et Rosen and Coccobius fulvus Compere et Annecke (Hymenoptera: Aphelinidae), which were used as biological control agents in a Japanese grove of Satsuma mandarin oranges, Citrus unshiu Marc. (Rutaceae). In this study, we examined whether the parasitoids regulated the scale population at lower levels after its initial decline. Specifically, we monitored the population dynamics of the scale and the rates of parasitism by the two parasitoids three times per year for 16 years following the introduction of the wasps. The two parasitoid species maintained a U. yanonensis density at 1/200 of the density prior to their introduction. When we excluded the wasps, the scale population grew at a rate that was more than fivefold that of a control (parasitoid‐infested) group. Although the rates of parasitism by C. fulvus fluctuated, they remained at relatively high levels, whereas those of A. yanonensis were 0% over the last 6 years. A repeated‐measures ANOVA indicated that scale density remained stable subsequent to its rapid decline. This showed that the parasitoids stabilized the scale population at a lower level than host plant limitations would have dictated, and strongly suggests that C. fulvus alone regulates the scale population density at an extremely low level. The latter finding contradicts other studies which have suggested that the two parasitoid species complement each other in regulating scale density. We discuss whether a behavioral refuge used by the scale against parasitoids, which we have demonstrated in an earlier study, might contribute to the observed stable host–parasitoid system at low densities.     

兀鹫在中国的分布

兀鹫(Gyps fulvus)隶属于隼形目(Falconiformes)鹰科(Accipitridae),被列入CITES附录Ⅱ,在国内几乎没有相应的研究。作者于2013年6月5日在西藏阿里地区改则县(33°6′52.2″N,85°39′9.18″E,海拔5 021 m)发现1只兀鹫。结合国内其他研究者的记录,此次发现增加了我们对兀鹫分布区的认识,表明了兀鹫在西藏的分布区可能被低估。根据以前研究者对兀鹫种群数量的估计值(100~300只)和平均群体大小(3只或4只或单只),以及本次的发现,我们认为兀鹫在新疆、西藏仍有未被发现的分布区,且在新疆、西藏的邻近省份可能存在其潜在分布区;此前兀鹫在西藏地区未有确切的观察记录或照片,本次记录可为西藏珍稀物种的保护提供依据。     

Special relationships instead of female dominance for redfronted lemurs,Eulemur fulvus rufus

Most lemurs yet studied in detail exhibit some mode of adult female social dominance over males. The known exception, a brown lemur subspecies known as rufous or redfronted lemurs (Eulemur fulvus rufus), forms multimale–multifemale social groups within which unambiguous dominance relations are not observed among adults. Resting groups of redfronted lemurs consistently include huddling adult male–female pairs whose males selectively scentmark and rub their heads in the scentmarks of their female huddling partners. Quantitative observations confirmed that some of these male–female pairs maintain special relationships satisfying all criteria originally developed in research on cercopithecine monkeys. Observations before, during, and after mating season, intergroup encounters, male transfers, and changes in male–female affiliations illuminated developmental and functional aspects of male–female partnerships. Each adult female in two semi-free-ranging study groups shared high rates of association, grooming, and agonistic support and low rates of agonistic interaction with one unrelated or distantly related adult male partner. Such affinity characterized small proportions of adult male–female relationships. Several males directed not only support but also aggression toward adult females with whom they sought to affiliate. All bonded males sought to copulate with their partners, and some appeared to ignore estrus in nonpartners. All females accepted copulation attempts from partners and some seemed to prefer their partners as mates. Partial synchronization of brief estrus periods together with concealed ovulation appeared to minimize chances for polygynous mating. Results support the view that the male–female pair is the fundamental social unit of E. fulvus and suggest that female partnership with individual males obviates dominance behavior, including female dominance, in this lemurid primate. Am. J. Primatol. 43:239–258, 1997. © 1997 Wiley-Liss, Inc.     

Measurement of body segment mass,center of gravity,and determination of moments of inertia by double pendulum in Lemur fulvus

The collection of data on physical parameters of body segments is a preliminary critical step in studying the biomechanics of locomotion. Little data on nonhuman body segment parameters has been published. The lack of standardization of techniques for data collection and presentation has made the comparative use of these data difficult and at times impossible. This study offers an approach for collecting data on center of gravity and moments of inertia for standardized body segments. The double swing pendulum approach is proposed as a solution for difficulties previously encountered in calculating moments of inertia for body segments. A format for prompting a computer to perform these calculations is offered, and the resulting segment mass data for Lemur fulvus is presented.