马蜂肠道菌的分离鉴定及产消化酶功能菌株的筛选

【背景】马蜂(Vespa mandarinia Smith)可以防治多种田间害虫,还具有药用价值,其肠道菌群结构和功能还有待研究。【目的】获得马蜂肠道可培养细菌并筛选出具有产消化酶功能的菌株,为理解肠道菌对宿主的影响机理及功能菌株的利用提供科学依据和研究材料。【方法】采用传统细菌分离培养法获得马蜂肠道菌,结合形态学以及16S rRNA基因序列分析进行鉴定;利用水解圈法分别筛选产蛋白酶、脂肪酶、淀粉酶和纤维素酶菌株;通过测量水解圈D与菌落直径d的比值,比较不同细菌的产酶能力。【结果】在马蜂肠道中共分离出6属10种细菌,其中芽孢杆菌属5种,肠球菌属、葡萄球菌属、明串珠菌属、乳球菌属和不动杆菌属各1种。从获得的61个菌株中筛选出6个具有产消化酶功能的菌株。其中,苏云金芽孢杆菌V44具有产蛋白酶、淀粉酶、脂肪酶和纤维素酶4种消化酶的能力;粪肠球菌V6具有产淀粉酶、蛋白酶和脂肪酶3种消化酶的能力;蜡样芽孢杆菌V43具有产蛋白酶、淀粉酶和纤维素酶3种消化酶的能力;粪肠球菌V20、蜡样芽孢杆菌V19和维德曼氏芽孢杆菌V22均具有产蛋白酶的能力。【结论】马蜂肠道细菌资源较丰富,部分有产消化酶的功能,可帮助马蜂消化食物,对宿主健康有一定影响。本研究筛选的6个菌株都能产蛋白酶,其中菌株V43和V44分别具有最强产淀粉酶和脂肪酶的能力,是可进一步开发利用的肠道功能菌株资源。     

Effects of late growing-season and late dormant-season prescribed fire on herbaceous vegetation in restored pine-grassland communities

Abstract. We compared the effects of late dormant-season and late growing-season prescribed fires on herbaceous species in restored shortleaf pine- (Pinus echinata) grassland communities in the Ouachita Highlands of western Arkansas. Herbaceous species richness, diversity, and total forb and legume abundance increased following fire. Late growing-season burns reduced distribution and abundance of panicums (primarily Panicum boscii, P. dichotomum, and P. linearifolium) while late dormant-season burns increased Panicum distribution and abundance. Density of legumes (such as Stylosanthes biflora) increased following frequent or annual dormant-season fires. However, season of fire influenced the distribution and abundance of fewer than 10 % of the species. Fire plays an essential role in pine-grassland communities by creating and maintaining open canopy conditions that perpetuate understory herbaceous plant communities.     

Seed banks of a rare wetland plant community: distribution patterns and effects of human-induced disturbance

Seed banks in rare shoreline communities (Nova Scotia, Canada), were examined in order to determine their role in the persistence of rare plant species. A pristine shoreline which supports globally and nationally significant Atlantic coastal plain species averaged 8500 seeds/m². Seedsweremost abundant high on the shore and where standing crop was greatest. Rare species, which made up 22% of the standing crop and litter of the adult vegetation, comprised only 4% of the seed bank. Common rushes such as Juncus canadensis and J. filiformis, were not well represented in the adult vegetation (5% of the standing crop and litter) but were abundant in the seed bank (52% of all seeds). Seed densities were on average, much lower on an intensely disturbed shoreline (1000 seeds/m²), where heavy all-terrain vehicle traffic had destroyed the adult vegetation. These results suggest that intense disturbances will destroy both existing vegetation and the seed bank and moderate disturbances will alter community composition so that common rushes will replace already endangered Atlantic coastal plain species.     

Adrenergic and cholinergic mediated glucose oxidation by rat parotid gland acinar cells during aging

A₂-phospholipase from Crotalus Adamanteus venom has been assayed using the fluorescent probe 2-all trans-parinoyllecithin. The hydrolysis of the lecithin in an “albumin-rich” incubation medium is paralleled with a fluorescence hyperpolarization. The mechanism of the hyperpolarization is discussed. The application of the method to assay phospholipases, allows detection of an activity under 1 nanomole/min and continuous monitoring of the hydrolysis.     

Secondary succession in disturbed Pinus-Quercus forests in the highlands of Chiapas,Mexico

We present floristic and structural data on serai plant communities (Old-Field, Grassland, Shrubland, and Early Successional, Mid-Successional, and Mature Forest) resulting from the current land use pattern in the Pinus-Quercus forests in the highlands of Chiapas, Mexico. The number of species ranged from 24 in the Old-Field stage up to 100 in the Mature Forest, and the shrub layer was richest in all the forested stands. An almost complete floristic replacement exists between the open and the forested communities. Quercus and Pinus dominate the canopy of old-growth stands, but their recruitment does not occur or is very low in the shade. Vigorous seedlings and saplings of these species are found only in the open serai stages or in forest gaps. Demographic and phytosociological data are used to indicate the successional role of dominant species in the forested stages. Some implications of the regional land use patterns for conservation and succession are discussed.     

Patterned fens in Scotland: evidence from vegetation and water chemistry

Mires with attributes similar to the patterned fens of boreal continental regions have recently been reported from northern Scotland. This paper reports on the vegetation and water chemistry of 18 of these sites. Most of the 18 mires displayed remarkable uniformity in their vegetation, with Carex lasiocarpa being a main character species. Major variation of plant communities is associated with microtopographical niches, similar to those found on ombrotrophic mire systems and secondarily with pH and conductivity of surface waters. Nine vegetation noda are described and compared with existing phytosociological associations and National Vegetation Classification (NVC) communities. The dominant Sphagnum - Carex communities are intermediate between the Oxycocco-Sphagnetea and the Caricion lasiocarpae and are thus difficult to assign to existing associations or to NVC communities. Although there is a large variation in pH of surface waters (3.9–6.6), mean measurements for terrestrial and aquatic communities are 5.12 and 5.51 respectively. pH levels are comparable with poor fen systems elsewhere in Britain and slightly higher than patterned fens in continental regions of Europe and North America. The vegeta-tional and chemical attributes of these sites therefore confirm the existence of true patterned fen systems in the British Isles.     

U1 small nuclear RNA variants differentially form ribonucleoprotein particles in vitro

The U1 small nuclear (sn)RNA participates in splicing of pre-mRNAs by recognizing and binding to 5′ splice sites at exon/intron boundaries. U1 snRNAs associate with 5′ splice sites in the form of ribonucleoprotein particles (snRNPs) that are comprised of the U1 snRNA and 10 core components, including U1A, U1-70K, U1C and the ‘Smith antigen’, or Sm, heptamer. The U1 snRNA is highly conserved across a wide range of taxa; however, a number of reports have identified the presence of expressed U1-like snRNAs in multiple species, including humans. While numerous U1-like molecules have been shown to be expressed, it is unclear whether these variant snRNAs have the capacity to form snRNPs and participate in splicing. The purpose of the present study was to further characterize biochemically the ability of previously identified human U1-like variants to form snRNPs and bind to U1 snRNP proteins. A bioinformatics analysis provided support for the existence of multiple expressed variants. In vitro gel shift assays, competition assays, and immunoprecipitations (IPs) revealed that the variants formed high molecular weight assemblies to varying degrees and associated with core U1 snRNP proteins to a lesser extent than the canonical U1 snRNA. Together, these data suggest that the human U1 snRNA variants analyzed here are unable to efficiently bind U1 snRNP proteins. The current work provides additional biochemical insights into the ability of the variants to assemble into snRNPs.     

云南卷叶小檗(小檗科)花与果实特征的变异式样

在云南省腾冲县通过野外居群取样,结合模式标本检查及统计分析方法,研究了小檗科卷叶小檗花和果实特征的变异式样。结果显示:(1)2013年5月,在12株卷叶小檗上取样的53朵花中,各花花被片数目为13~18个,平均为15.25±0.96个,其中,来自11株植物的34朵花都具有15个花被片,占个体总数的91.67%,占花总数的64.15%;此外,各花内部与雄蕊对生的6个花被片先端缺裂。(2)2013年12月,在12株卷叶小檗上分别取样的20个成熟果实中,单个果实内种子数目为1~4个,平均为1.79±0.48个,其中74.17%的果实都含有2粒种子;2013年5月,自6株卷叶小檗上采集的2012年宿存的150个果实中,单个果实内种子数目为1~3个,平均为2.11±0.43个,其中80.67%的果实都含有2粒种子;而已有文献皆记载卷叶小檗子房具胚珠2个。(3)在卷叶小檗个体内花和果实特征的变异系数中,花被片数目(0.05±0.03)果实长度(0.07±0.02)果实宽度(0.11±0.02)果柄长度(0.16±0.05)果实内种子数目(0.25±0.08)花被片长度(0.36±0.04)花被片宽度(0.38±0.04)。(4)对《中国植物志》小檗属中卷叶小檗花和果实等重要分类学性状特征进行了订正,同时为该种一直空缺的绘图补充了图片资料。     

Higher acidification rates in fens with phosphorus enrichment

Question: Why is bryophyte succession in eutrophicated fens faster than in natural fens? Location: Mineral‐rich fens in The Netherlands and NW Europe. Methods: Literature review on the ecology of four bryophyte species in various successional types as observed in Dutch fens. Results: Bryophyte succession in eutrophicated fens from the brown moss Calliergonella cuspidata to Sphagnum squarrosum is much faster than in natural fens with species shifts from Scorpidium scorpioides to Sphagnum subnitens. Under P‐poor conditions, the brown moss stage is stabilized as long as mineral‐rich water is supplied. This is because S. scorpioides is tolerant of rainwater, is a strong competitor and can counteract acidification to some extent while S. subnitens is intolerant to groundwater and has low growth rates and low acidification capacity. In contrast, the Sphagnum stage is stable after rapid succession from rich‐fen mosses under P‐rich conditions. Calliergonella cuspidata has suboptimal growth in rainwater, possibly due to ammonium toxicity, while the high growth rates of S. squarrosum in nutrient‐rich and highly acidic groundwater allow early establishment and rapid expansion. Conclusions: If measures to improve fen base status occur in environments of increased nutrient (P) availability, the management may not lead to the desired restoration of brown moss stages, but instead to rapid acidification by S. squarrosum.     

Cautionary Tales for Aspiring Species or The Beast's Book of Blunders

Find out what links J.B.S. Haldane, the twofold cost of sex and the British Bulldog in this anthology of comic verse – it's much more entertaining and informative than your average science article.