Genetic regulation of flower development

Flower development provides a model system to study mechanisms that govern pattern formation in plants. Most flowers consist of four organ types that are present in a specific order from the periphery to the centre of the flower. Reviewed here are studies on flower development in two model species:Arabidopsis thaliana andAntirrhinum majus that focus on the molecular genetic analysis of homeotic mutations affecting pattern formation in the flower. Based on these studies a model was proposed that explains how three classes of regulatory genes can together control the development of the correct pattern of organs in the flower. The universality of the basic tenets of the model is apparent from the analysis of the homologues of theArabidopsis genes from other plant species     

Development Models for the Filth Fly ParasitoidsSpalangia gemina, S. cameroni,andMuscidifurax raptor(Hymenoptera: Pteromalidae) under Constant and Variable Temperatures

Development rates were determined for three pteromalid parasitoids of houseflies under constant and varying temperatures from 15 to 35°C.Muscidifurax raptorGirault and Sanders was the fastest developing species, with females completing development in 13.8 days at 32.5°C and 66.5 days at 15°C.Spalangia geminaBoucek females completed development in 20.8 days at 30.0°C and 161 days at 15.0°C, whereasS. cameroniPerkins females completed development in 20.6 days at 30.0°C and 155.5 days at 15.0°C. Male development times were 90.3% of those for femaleS. geminaand 92.7 and 88.6% of those for femaleS. cameroniandM. raptor,respectively. Parasitoid survival was very low at 35°C for all species and noSpalangiasurvived constant exposure to 15.0°C. Exposure to these lethal temperatures for shorter periods indicated that the parasitoids can tolerate them well under conditions more typical of the field. Development rates were modeled using biophysical and degree-day models and the models were tested for their ability to predict development under fluctuating conditions (24–36°C). Neither model was superior for all three species because of interspecific differences in the parasitoids' responses to high temperatures. Agreement between predicted and observed development times for all three species was achieved by small empirical adjustments of a key parameter in the biophysical model.     

Transgenic animals as a tool for studying the effect of the c-myc proto-oncogene on cardiac development

Transgenic animals provide a model system to elucidate the role of specific proteins in development. This model is now being used increasingly in the cardiovascular system to study cardiac growth and differentiation. During cardiac myocyte development a transition occurs from hyperplastic to hypertrophic growth. In the heart the switch from myocyte proliferation to terminal differentiation is synchronous with a decrease in c-myc mRNA abundance. To determine whether c-myc functions to regulate myocyte proliferation and/or differentiation, we examined the in vivo effect of increasing c-myc expression during fetal development and of preventing the decrease in c-myc mRNA expression that normally occurs during myocyte development. The model system used was a strain of transgenic mice exhibiting constitutive expression of c-myc mRNA in cardiac myocytes throughout development. Increased c-myc mRNA expression is associated with both atrial and ventricular enlargement in the transgenic mice. This increase in cardiac mass is secondary to myocyte hyperplasia, with the transgenic hearts containing greater than twice as many myocytes as nontransgenic hearts. The results of this study indicate that constitutive expression of c-myc mRNA in the heart during development results in enhanced hyperplastic growth, and suggest a regulatory role for the c-myc protooncogene in cardiac myogenesis.     

Growth and development of immature life stages ofPropylaea 14-punctata L. andCoccinella 7-punctata L. [Col.: Coccinellidae] simulated by the metabolic pool model

The conversion of aphid prey tissue (Acyrthosiphon pisum Harris) into predator biomass (immature life stages ofPropylaea 14-punctata L. andCoccinella 7-punctata L.) is calculated by plotting weight gain against assimilation (i.e. consumption minus egestion). This concept is added to the metabolic pool model byGutierrez et al. (1981) that enables the simulation of growth and development of a predator on a physiological basis. Physiological time is expressed in daydegrees above lower development thresholds for both species. Visual examination of observed and calculated values showed that the model satisfactorily describes the growth patterns of the above predators.      

用于药物评价的体外心脏组织模型研究进展

候选药物对心脏的毒副作用是其在开发过程中被淘汰的重要原因之一.传统药物评价所采用的动物模型存在种属差异、成本高、效率低等缺陷.因此,近年来随着干细胞和生物打印等技术的快速发展,体外心脏组织模型的构建受到了越来越多地关注.本文追踪体外心脏模型构建的起源与发展,综述模型所利用的心肌细胞来源以及二维、三维模型构建的相关技术与方法,着重阐述心肌组织模型血管化的重要性及研究进展,并对该领域未来的发展方向进行展望,以期为体外心肌组织模型在药物评价方面的研究和应用提供新思路.     

RagA和Nprl2在果蝇肠道发育中的调节作用关系

动物胃肠道是食物消化和营养吸收器官,对机体健康至关重要。果蝇与哺乳动物的肠道在细胞组成、遗传调控等方面高度相似,是研究肠道发育的良好模型。体外培养细胞中的研究发现,Nprl2通过作用于Rag GTPase,抑制雷帕霉素靶点复合物1(target of rapamycin complex 1,TORC1)的活性,参与细胞代谢的调节。前期报道nprl2突变果蝇具有前胃增大、消化能力降低等肠道衰老相关表型。但对于Nprl2是否通过Rag GTPase调控肠道发育等方面尚不清楚。为了探究Rag GTPase在Nprl2调控果蝇肠道发育中的作用,本研究利用遗传杂交结合免疫荧光等方法对RagA敲减和nprl2突变果蝇的肠道形态、肠道细胞组成等方面进行研究。发现单独敲减RagA可以引起肠变粗、前胃增大等表型,敲减RagA能挽救nprl2突变体中肠道变细、分泌型细胞减少的表型,但并不能挽救nprl2突变体中前胃增大的表型。以上结果表明,RagA在肠道发育中发挥重要作用,Nprl2通过作用于Rag GTPase调节肠道细胞分化和肠道形态,但Nprl2对前胃发育和肠道的消化功能的调节可能通过不依赖于Rag GTPase的机制实现。     

Constraints-based genome-scale metabolic simulation for systems metabolic engineering

Random mutagenesis and selection approaches used traditionally for the development of industrial strains have largely been complemented by metabolic engineering, which allows purposeful modification of metabolic and cellular characteristics by using recombinant DNA and other molecular biological techniques. As systems biology advances as a new paradigm of research thanks to the development of genome-scale computational tools and high-throughput experimental technologies including omics, systems metabolic engineering allowing modification of metabolic, regulatory and signaling networks of the cell at the systems-level is becoming possible. In silico genome-scale metabolic model and its simulation play increasingly important role in providing systematic strategies for metabolic engineering. The in silico genome-scale metabolic model is developed using genomic annotation, metabolic reactions, literature information, and experimental data. The advent of in silico genome-scale metabolic model brought about the development of various algorithms to simulate the metabolic status of the cell as a whole. In this paper, we review the algorithms developed for the system-wide simulation and perturbation of cellular metabolism, discuss the characteristics of these algorithms, and suggest future research direction.     

High-efficiency Agrobacterium-mediated transformation of Brachypodium distachyon inbred line Bd21-3

Brachypodium distachyon (Brachypodium) is a small grass with biological attributes (rapid generation time, small genome, diploid accessions, small stature and simple growth requirements) that make it suitable for use as a model system. In addition, a growing list of genomic resources have been developed or are currently under development including: cDNA libraries, BAC libraries, EST sequences, BAC end sequences, a physical map, genetic markers, a linkage map and, most importantly, the complete genome sequence. To maximize the utility of Brachypodium as a model grass it is necessary to develop an efficient Agrobacterium-mediated transformation system. In this report we describe the identification of a transformable inbred diploid line, Bd21-3, and the development of a transformation method with transformation efficiencies as high as 41% of co-cultivated calluses producing transgenic plants. Conducting the co-cultivation step under desiccating conditions produced the greatest improvement in transformation efficiency.     

Spirula—a window to the embryonic development of ammonoids? Morphological and molecular indications for a palaeontological hypothesis

Nautilus is not suitable as a model organism to infer biological functions, embryonic development, or mode of life in ammonoids. A brief review of the available morphological data is given and molecular data are added to discuss the usefulness of Spirula as a biological proxy for ammonoids. Indeed, there are many morphological hints indicating that Spirula could be a useful model organism for approaching the embryonic development of ammonoids. The molecular data seem to support this hypothesis. However, a universal model character of Spirula cannot be detected as, e.g., the mode of feeding probably differs between Spirula and ammonoids.     

Regulation of stipule development by <Emphasis Type="Italic">COCHLEATA</Emphasis> and <Emphasis Type="Italic">STIPULE</Emphasis>-<Emphasis Type="Italic">REDUCED</Emphasis> genes in pea <Emphasis Type="Italic">Pisum sativum</Emphasis>

Pisum sativum L., the garden pea crop plant, is serving as the unique model for genetic analyses of morphogenetic development of stipule, the lateral organ formed on either side of the junction of leafblade petiole and stem at nodes. The stipule reduced (st) and cochleata (coch) stipule mutations and afila (af), tendril-less (tl), multifoliate-pinna (mfp) and unifoliata-tendrilled acacia (uni-tac) leafblade mutations were variously combined and the recombinant genotypes were quantitatively phenotyped for stipule morphology at both vegetative and reproductive nodes. The observations suggest a role of master regulator to COCH in stipule development. COCH is essential for initiation, growth and development of stipule, represses the UNI-TAC, AF, TL and MFP led leafblade-like morphogenetic pathway for compound stipule and together with ST mediates the developmental pathway for peltate-shaped simple wild-type stipule. It is also shown that stipule is an autonomous lateral organ, like a leafblade and secondary inflorescence.     

基于Vortex模型分析金沙江水电开发对圆口铜鱼种群生存力的影响

圆口铜鱼(Coreius guichenoti)是长江上游特有鱼类,研究金沙江梯级水电开发背景下圆口铜鱼种群生存力变化对该物种的保护具有重要意义。Vortex模型在传统种群评估方法的基础上,引入种群年龄结构、繁殖体制、性比等因素,并考虑了环境、灾害、遗传等随机性对种群的影响,可模拟种群数量和生存力变化特征,是一种应用广泛的种群生存力分析模型。基于1981-2021年金沙江圆口铜鱼资源调查数据,采用Vortex模型构建了金沙江中下游干流大规模水电开发前、后两个时期圆口铜鱼种群生存力分析模型,考虑了水电开发下,水温、流速等环境变化对圆口铜鱼种群的影响,对比了两个时期圆口铜鱼种群数量、结构及生存力等。结果表明:水电开发前,严重过度捕捞对圆口铜鱼种群产生了显著威胁,10年内种群数量下降了12.5%,百年内种群内禀增长率为0.085,种群的生存和繁殖能力较稳定,灭绝概率为1%;水电开发后,10年内种群数量下降了42%,百年内种群内禀增长率降至-0.087,灭绝概率增大至36.1%,种群平均灭绝时间为83.7年,圆口铜鱼抵抗环境干扰的种群恢复能力降低,种群生存力受到影响。     

铁皮石斛泛素结合酶DoUBC9的克隆鉴定与表达分析

目的:本研究旨在探讨泛素结合酶UBC9在铁皮石斛原球茎发育过程中的分子机制,方法:利用生物信息学手段,从已获得的铁皮石斛基因组中鉴定出UBC9基因,命名为DoUBC9,并利用RACE技术,克隆出DoUBC9 3’端,通过与基因组序列拼接,获得完整序列。结果:本研究首次从铁皮石斛基因组中运用生物信息学的方法,鉴定出DoUBC9,并通过RACE技术克隆后拼接,得到完整的DoUBC9,基因全长为7176bp,CDS长为447bp,共编码148个氨基酸。亚细胞定位预测结果表明,DoUBC9大概率分布于分泌囊泡和质膜上。序列比对和进化树分析表明,铁皮石斛Do UBC9和其他物种中的UBC9拥有高度保守的UBCc结构域,进化关系高度保守。qRT-PCR分析表明,在不同组织部位中,DoUBC9在愈伤组织中的表达量最高、叶中表达量最小;在原球茎发育过程中,在P1时期具有最高表达量,其他各时期表达量较小,表明该基因可能促进了植物体的细胞快速分裂与生长。结论:通过分子建模方式,首次构建出DoUBC9蛋白的基本模型,并通过不同的评价方式确定了以人泛素结合酶E2 H结构(2Z5D)为模板的为最优模型。     

Patterning in the cellular slime moulds

The aim of the present article is to derive and illustrate in a simple form some of the important concepts in developmental biology. The development of the cellular slime mouldDictyostelium discoideum is an ideal model system for this purpose. I will outline the development of this organism at its multicellular stages and review some relevant studies focusing on the control of cell differentiation and pattern formation while deriving some key concepts in the current thinking about the control of development.     

Effect of Temperature on Development and Fecundity of the Predaceous Plant Bug <Emphasis Type="Italic">Deraeocoris brevis</Emphasis> Reared on <Emphasis Type="Italic">Ephestia kuehniella</Emphasis> Eggs

Temperature-dependent development and oviposition component models were developed for Deraeocoris brevis (Uhler) (Hemiptera: Miridae). Egg development times decreased with increasing temperature and ranged from 35.8 d at 15 °C to 6.7 d at 32 °C. Total development times of nymphs reared on frozen Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs decreased from an estimated 55.6 d at 15 °C to 9.2 d at 32 °C and 10.0 d at 34.6 °C. By fitting linear models to the data the lower developmental threshold temperatures for eggs, small nymphs (1st to 3rd instar), large nymphs (4th to 5th instar), and all nymphs combined were calculated as 10.5, 12.5, 11.8, and 11.9 °C, respectively. The thermal constants were 144.1, 90.3, 95.0, and 190.8 degree-days for each of the above stages. The non-linear model was based on a Gaussian equation, which fit the relationship between development rate and temperature well for all stages. The Weibull function provided a good fit for the distribution of development times of each stage. Adult longevity decreased with increasing temperature and ranged from 52.9 d at 21.7 to 16.8 d at 32.0 °C. D. brevis had a maximum fecundity of 471 eggs per female at 24 °C, which declined to 191 eggs per female at 32 °C. Also, three temperature-dependent components for an oviposition model of D. brevis were developed including models for total fecundity, age-specific cumulative oviposition rate, and age-specific survival rate.     

Genome-scale reconstruction and <Emphasis Type="Italic">in silico</Emphasis> analysis of the <Emphasis Type="Italic">Clostridium acetobutylicum</Emphasis> ATCC 824 metabolic network

To understand the metabolic characteristics of Clostridium acetobutylicum and to examine the potential for enhanced butanol production, we reconstructed the genome-scale metabolic network from its annotated genomic sequence and analyzed strategies to improve its butanol production. The generated reconstructed network consists of 502 reactions and 479 metabolites and was used as the basis for an in silico model that could compute metabolic and growth performance for comparison with fermentation data. The in silico model successfully predicted metabolic fluxes during the acidogenic phase using classical flux balance analysis. Nonlinear programming was used to predict metabolic fluxes during the solventogenic phase. In addition, essential genes were predicted via single gene deletion studies. This genome-scale in silico metabolic model of C. acetobutylicum should be useful for genome-wide metabolic analysis as well as strain development for improving production of biochemicals, including butanol. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. J. L. and H. Y. equally contributed to this work.     

Recent advances in Pelargonium in vitro regeneration systems

Recent advances in the development of protocols for in vitro culture and genetic manipulation have provided new avenues for the development of novel varieties of Pelargonium and for use as model systems for investigating the factors controlling plant morphogenesis. Optimized techniques of meristem culture have supplemented the culture indexing methods in commercial greenhouse production resulting in availability of large-scale pathogen indexed planting material. Currently, technologies are available for the mass in vitro propagation of F1 hybrid Pelargonium through both organogenesis and somatic embryogenesis. The somatic embryogenesis model system has allowed researchers to identify critical factors controlling plant morphogenesis in vitro such as regulation of regeneration by growth regulators, choice of explant and characterization of induction and expression phases of morphogenesis in Pelargonium. Also, optimization of technologies for genetic transformation of Pelargonium opened up the possibilities for developing genotypes with novel characters, including resistance to some of the major diseases. Finally, the development of regeneration systems for Pelargonium spp. has facilitated conventional crop improvement programs, thereby providing a valuable resource to the horticultural industry.     

Ferritins, bacterial virulence and plant defence

The enterobacterial pathogen Erwinia chrysanthemi causes soft rot diseases on a wide range of plants, including the model plant Arabidopsis thaliana. This bacterium proliferates in the host by secreting a set of pectin degrading enzymes responsible for symptom development. In addition, survival of this bacterium in planta requires two high-affinity iron acquisition systems mediated by siderophores and protective systems against oxidative damages, suggesting the implication by both partners of accurate mechanisms controlling their iron homeostasis under conditions of infection. In this review, we address this question and we show that ferritins both from the pathogen and the host are subtly implicated in the control of this interplay.     

Effect of seed-specific expression of the <Emphasis Type="Italic">ipt</Emphasis> Gene on <Emphasis Type="Italic">Nicotiana tabacum</Emphasis> L. seed composition

A transgenic approach to manipulation of endosperm development has been investigated. Nicotiana tabacum cv. Xanthi, an endosperm-containing dicotyledon, has been used as a model plant and the 2.6 kb wheat high molecular weight (HMW) glutenin subunit 12 promoter has been used fused either to the gus reporter gene (HMWgus construct)—to study promoter characteristics—or to the Agrobacterium ipt gene—to study the effect of cytokinin (CK) over-expression on assimilate accumulation in the seed. In transgenic tobacco the promoter:gus fusion showed that HMW is an endosperm-specific promoter with maximum expression 20 days after anthesis (DAA), corresponding to the mid to late stages of seed development. Transgenic plants containing the HMWipt construct showed no morphological abnormalities but they had an average increase in seed weight and total ethanol-insoluble carbohydrates and protein content of 8.1%, 7.0% and 8.3%, respectively. SDS PAGE analysis demonstrated that the effect on protein accumulation was non-specific. The highest values of the parameters analysed correlated with moderate increases in the levels of biologically active CKs. These results suggest that ectopic expression of small amounts of CKs can be used to increase storage assimilate accumulation without a detrimental effect on development.     

澳洲杨(大戟科)胚珠及其种子附属结构的个体发育研究

以澳洲杨的胚珠及其种子为材料,运用光学显微镜和电镜扫描的方法对其从胚珠发生直到种子成熟的个体发育过程和结构进行观察,同时与鸭脚西番莲的种子附属结构的发育过程进行对比研究。结果表明:(1)澳洲杨的珠孔类型为外珠孔类型,种子附属结构起源于珠孔而非珠柄,其为种阜,而非假种皮。(2)鸭脚西番莲的珠孔类型为内珠孔类型,种子附属结构起源于珠柄,并且最终将珠孔包被,其为真正的假种皮结构。通过种阜与假种皮的不同个体发育过程,建立了大戟科种阜与假种皮的不同发育模式,并对种子附属结构的生物学功能及其暗示的不同植物进化路径进行了讨论。     

Development of a RIVPACS-type predictive model for bioassessment of wadeable streams in Wyoming

RIVPACS models produce a community-level measure of biological condition known as O/E, which is derived from a comparison of the observed (O) biota with those expected (E) to occur in the absence of anthropogenic stress. We used benthic macroinvertebrate and environmental data collected at 925 stream monitoring stations, from 1993 to 2001, to develop, validate, and apply a RIVPACS model to assess the biological condition of wadeable streams in Wyoming. From this dataset, 296 samples were identified as reference, 157 of which were used to calibrate the model, 46 to validate it, and 93 to examine temporal variability in reference site O/E-values. We used cluster analyses to group the model development reference sites into biologically similar classes of streams and multiple discriminant function analysis to determine which environmental variables best discriminated among reference groups. A suite of 14 categorical and continuous environmental variables best discriminated among 15 reference groups and explained a large proportion of the natural variability in biota within the reference dataset. Eleven of the predictor variables were derived from GIS. As expected, mean O/E-values for reference sites used in model development and validation were near unity and statistically similar. Temporal variability in O/E-values for reference sites was low. Test site values ranged from 0 to 1.45 (mean = 0.73). The model was accurate in both space and time and precise enough (S.D. of O/E-values for calibration data = 0.17) to detect modest alteration in biota associated with anthropogenic stressors. Our model was comparable in performance to other RIVPACS models developed in the United States and can produce effective assessments of biological condition over a broad, ecologically diverse region. We also provide convincing evidence that RIVPACS models can be developed primarily with GIS-based predictor variables. This framework not only simplifies the extraction of predictor variable information while potentially reducing expenditures of time and money in the collection of predictor variable information, but opens the door for development and/or application of RIVPACS models in regions where there is a paucity of local-scale, abiotic information.