Combined use of dbcAMP and IBMX minimizes the damage induced by a long‐term artificial meiotic arrest in mouse germinal vesicle oocytes

Phosphodiesterase (PDE)‐mediated reduction of cyclic adenosine monophosphate (cAMP) activity can initiate germinal vesicle (GV) breakdown in mammalian oocytes. It is crucial to maintain oocytes at the GV stage for a long period to analyze meiotic resumption in vitro. Meiotic resumption can be reversibly inhibited in isolated oocytes by cAMP modulator forskolin, cAMP analog dibutyryl cAMP (dbcAMP), or PDE inhibitors, milrinone (Mil), Cilostazol (CLZ), and 3‐isobutyl‐1‐methylxanthine (IBMX). However, these chemicals negatively affect oocyte development and maturation when used independently. Here, we used ICR mice to develop a model that could maintain GV‐stage arrest with minimal toxic effects on subsequent oocyte and embryonic development. We identified optimal concentrations of forskolin, dbcAMP, Mil, CLZ, IBMX, and their combinations for inhibiting oocyte meiotic resumption. Adverse effects were assessed according to subsequent development potential, including meiotic resumption after washout, first polar body extrusion, early apoptosis, double‐strand DNA breaks, mitochondrial distribution, adenosine triphosphate levels, and embryonic development. Incubation with a combination of 50.0 μM dbcAMP and 10.0 μM IBMX efficiently inhibited meiotic resumption in GV‐stage oocytes, with low toxicity on subsequent oocyte maturation and embryonic development. This work proposes a novel method with reduced toxicity to effectively arrest and maintain mouse oocytes at the GV stage.     

The demonstration of a novel sulfur cycle-based wastewater treatment process: Sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI®) biological nitrogen removal process

Saline water supply has been successfully practiced for toilet flushing in Hong Kong since 1950s, which saves 22% of freshwater in Hong Kong. In order to extend the benefits of saline water supply into saline sewage management, we have recently developed a novel biological organics and nitrogen removal process: the Sulfate reduction, Autotrophic denitrification, and Nitrification Integrated (SANI®) process. The key features of this novel process include elimination of oxygen demand in organic matter removal and production of minimal sludge. Following the success of a 500‐day lab‐scale trial, this study reports a pilot scale evaluation of this novel process treating 10 m³/day of 6‐mm screened saline sewage in Hong Kong. The SANI® pilot plant consisted of a sulfate reduction up‐flow sludge bed (SRUSB) reactor, an anoxic bioreactor for autotrophic denitrification and an aerobic bioreactor for nitrification. The plant was operated at a steady state for 225 days, during which the average removal efficiencies of both chemical oxygen demand (COD) and total suspended solids (TSS) at 87% and no excess sludge was purposefully withdrawn. Furthermore, a tracer test revealed 5% short circuit flow and a 34.6% dead zone in the SRUSB, indicating a good possibility to further optimize the treatment capacity of the process for full‐scale application. Compared with conventional biological nitrogen removal processes, the SANI® process reduces 90% of waste sludge, which saves 35% of the energy and reduces 36% of fossil CO₂ emission. The SANI® process not only eliminates the major odor sources originating from primary treatment and subsequent sludge treatment and disposal during secondary saline sewage treatment, but also promotes saline water supply as an economic and sustainable solution for water scarcity and sewage treatment in water‐scarce coastal areas. Biotechnol. Bioeng. 2012; 109: 2778–2789. © 2012 Wiley Periodicals, Inc.     

A framework for estimating the fixation time of an advantageous allele in stepping-stone models

Determining how population subdivision increases the fixation time of an advantageous allele is an important problem in evolutionary genetics as this influences many processes. Here, I lay out a framework for calculating the fixation time of a positively selected allele in a subdivided population, as a function of the number of demes present, the migration rate between them and the manner in which they are connected. Using this framework, it becomes clear that a beneficial allele's fixation time is significantly reduced through migration continuously introducing copies of the allele into a newly colonized subpopulation, increasing its frequency within these demes. The effect that migration has on allele frequency needs to be explicitly taken into account to produce a realistic estimate of fixation time. This behaviour is most prominent when demes are arranged on a two-dimensional torus, in comparison with populations where demes are arranged in a circle. This is because each subpopulation is connected to several neighbours over a torus, so that there are multiple paths that an allele can take in order to fix. As a consequence, some demes experience a greater influx and efflux of migrants than others. Analytical results are found to be very accurate when compared to stochastic simulations, and are generally robust if there are a large number of demes, or if the allele is weakly selected for.     

地椒花蜜腺发育的解剖学观察

通过显微和亚显微观察对地椒花蜜腺的发育进行了研究。地椒花蜜腺位于子房基部的花盘上,属于盘状蜜腺,新鲜时呈绿色。蜜腺由分泌表皮和泌蜜组织组成,分泌表皮为一层细胞,表皮细胞角质膜较厚,表皮上分布着大量的气孔器,气孔器突出于表面;泌蜜组织细胞多层。花盘中央有维管束通向子房,在维管束和泌蜜组织之间有４￣５层大型的薄壁细胞。蜜腺由花盘的表皮及其内侧相邻的细胞发育而来,在发育过程中,其细胞中的液泡和贮藏的淀粉     

试议新型高蛋白植物杂交酸模的开发利用

1　引　言新型高蛋白植物杂交酸模 (以下简称杂交酸模 ) ,最先是由前苏联乌克兰国家科学院中心植物园作物研究所的乌切乌什博士 ,于 2 0世纪 70年代利用天山酸模 (Ｒｕｍｅｘｔｉａｎｓｃｈａｎｉｃｕｓ)为父本及巴天酸模 (Ｒ .ｐｕｔｉｅｎｔｉｕ)为母本 ,通过杂交技术历时 1 0多年而育成的牧草新品种。在国外 ,俄罗斯、乌克兰、荷兰、波兰、英国、法国、德国、西班牙、挪威等欧洲国家 ,以及印度、非洲一些国家都在开展酸模的生产和利用的研究 ,包括生物特性、化学成分、营养价值、栽培技术以及加工利用等 ,并取得某种进展。例如俄罗斯的罗…     

Progress in deciphering the information content of the ‘glycome’ – a crescendo in the closing years of the millennium

The closing years of the second millennium have been uplifting for carbohydrate biology. Optimism that oligosaccharide sequences are bearers of crucial biological information has been borne out by the constellation of efforts of carbohydrate chemists, biochemists, immunochemists, and cell- and molecular biologists. The direct involvement of specific oligosaccharide sequences in protein targeting and folding, and in mechanisms of infection, inflammation and immunity is now unquestioned. With the emergence of families of proteins with carbohydrate-binding activities, assignments of information content for defined oligosaccharide sequences will become more common, but the pinpointing and elucidation of the bioactive domains on oligosaccharides will continue to pose challenges even to the most experienced carbohydrate biologists. The neoglycolipid technology incorporates some of the key requirements for this challenge: namely the resolution of complex glycan mixtures, and ligand binding coupled with sequence determination by mass spectrometry.     

木耳栽培菌株酯酶同工酶的酶谱多样性研究

采用聚丙烯酰胺凝胶电泳技术对木耳（Ａｕｒｉｃｕｌａｒｉａａｕｒｉｃｕｌａ（Ｈｏｏｋ）Ｕｎｄｅｒｗ）１０个栽培菌株酯酶同工酶的酶谱多样性进行了研究。１０个供试菌株的幼龄菌丝（７ｄ）中仅检测到２５条酶带,各个菌株分别具有２～３条酶带,１０个菌株仅有２种酶谱类型;老龄菌丝（７２ｄ）中共检测到４４条酶带,各个菌株分别具有３～６条酶带,１０菌株共有８种酶谱类型。研究表明,木耳双核体菌丝中某些酯酶同工酶基因位点在一定的发育时期才开始表达,老龄菌丝酯酶同工酶酶谱在木耳菌株鉴别和遗传育种研究中具有更大的应用价值。     

Effects of host instar and size on parasitization efficiency and life history parameters ofOpius dissitus

The braconid parasitoidOpius dissitus Muesebeck (Hymenoptera, Braconidae) produced 1.7 to 3 times more offspring when provided second and third instar leafminers (Liriomyza sativae Blanchard) as compared to first instars. Females arising from parasitization of different instars did not differ significantly in numbers of chorionated eggs in their ovaries at adult eclosion. Development time was prolonged by about two days when parasitoid oviposition occurred in first, as compared to third instar hosts. Parasitoid length was positively correlated with host weight (r²=0.75). Because only 7% of variation in host weight could be explained by host density, parasitoid length varied considerably among hosts reared at the same density. Longevity and lifetime fecundity of parasitoids were inversely related to the weight of their hosts.     

DEVELOPMENTAL STUDIES IN PORPHYRA (BANGIOPHYCEAE). II. CHARACTERIZATIO OF THE MAJOR LECTIN BINDING GLYCOPROTEINS IN DIFFERENTIATED REGIONS OF THE PORPHYRA PERFORATA THALLUS1

Detergent soluble extracts of differentiated regions of the Porphyra perforata J. Ag. thallus (holdfast, rhizoidal, vegetative and reproductive cells) were fractionated on sodium dodecyl sulfate polyacrylamide gels. Glycoproteins were identified by their lectin affinity. Extracts from all areas of the thallus contained glycoproteins, but the staining patterns were different for each region with each of the lectins tested: concanavalin A, Ulex europeaus agglutinin, Ricinus communis agglutinin, soybean agglutinin and peanut agglutinin. These data indicate that the morphologically distinct regions of the thallus also differ biochemically. Analysis of the lectin blots revealed the presence of tissue-specific glycoproteins in the five thallus areas. Such unique glycoproteins could be used as markers of differentiation in this species.