Plasmid promiscuity and chastity and its uses

Bacterial plasmids are obligate and intracellular genetic elements that replicate and are maintained autonomously from the chromosome. They are ubiquitous. Some of them are relatively more promiscuous than others. Plasmid genetic systems that contribute to relative promiscuity or chastity in naturally occurring plasmids are described and discussed. Both the promiscuity and the chastity of plasmid-based genetic systems have applications in bacterial molecular genetics, in the production of recombinant DNA products and in the breeding and use of desirable bacteria. The role of these systems in such applications is considered.     

Crustacean peptide and peptide-like pheromones and kairomones

Crustacean peptide pheromones, kairomones, and substituted amino sugar kairomones are reviewed from a historical perspective. These crustacean information molecules are secondary functions of structural polymers. They are partial hydrolysis products, generated usually by the action of trypsin-like enzymes on proteins, and glycosidase enzymes on glycoproteins and proteoglycans. Structure-function studies based upon synthetic mimics of peptide information molecules show neutral amino acids with a basic carboxyl terminal are active in modifying physiological and or behavioral responses. Behaviorally active substituted amino sugar mimics are disaccharide hydrolysis products of heparin and chondroitin sulfate. Similar molecules are also used as information molecules by a variety of other marine organisms indicating they are a common biological theme.     

炭疽疫苗及治疗药物筛选和评价模型研究进展

炭疽疫苗和治疗药物的研究是近年来国际上研究热点之一,由于对它们的有效性研究不能在人体进行,因此实验模型的选择就特别重要.目前常用的细胞模型主要包括CHO细胞和J774A.1细胞.动物模型种类较多,包括小鼠、大鼠、豚鼠、兔和猴等都被作为炭疽的动物模型加以研究.由于模型选择的差异,实验结果常出现较大差异,甚至得到相反的结果.回顾了以往在细胞和动物模型上进行的炭疽实验,分析选择炭疽研究模型的原则和依据.同时,为探讨不同模型之间产生实验结果差异的原因,简要介绍了炭疽杆菌的致病机理,以及炭疽疫苗和治疗药物的研究进展.     

Innexin and pannexin channels and their signaling

Innexins are bifunctional membrane proteins in invertebrates, forming gap junctions as well as non-junctional membrane channels (innexons). Their vertebrate analogues, the pannexins, have not only lost the ability to form gap junctions but are also prevented from it by glycosylation. Pannexins appear to form only non-junctional membrane channels (pannexons). The membrane channels formed by pannexins and innexins are similar in their biophysical and pharmacological properties. Innexons and pannexons are permeable to ATP, are present in glial cells, and are involved in activation of microglia by calcium waves in glia. Directional movement and accumulation of microglia following nerve injury, which has been studied in the leech which has unusually large glial cells, involves at least 3 signals: ATP is the “go” signal, NO is the “where” signal and arachidonic acid is a “stop” signal.     

Similar and divergent features in mammalian and yeast prions

Mammalian transmissible spongiform encephalopathies are likely due to the propagation of an abnormal form of a constitutive protein instead of traditional genetic material (nucleic acids). Such infectious proteins, which are termed prions, exist in yeast. They are at the origin of a number of phenotypes that are inherited in a non-Mendelian manner. These prions are very useful to dissect the molecular events at the origin of this structure-based inheritance. The properties of mammalian and yeast prions are presented and compared. This review highlights a number of similarities and differences.     

Duplication and divergence in humans and chimpanzees

It has become a truism that we humans are genetically about 99% identical to chimpanzees. The origins of this assertion are clear: among early studies of DNA sequences, nucleotide identity between humans and chimpanzees was found to average around 98.9%.(1) However, this figure is correct only with respect to regions of the genome that are shared between humans and chimpanzees. Often ignored are the many parts of their genomes that are not shared. Genomic rearrangements, including insertions, deletions, translocations and duplications, have long been recognized as potentially important sources of novel genomic material(2,3) and are known to account for major genomic differences between humans and chimpanzees.(4) Further, such changes have been implicated in a number of genetic disorders, such as DiGeorge, Angelman/Prader-Willi and Charcot-Marie-Tooth syndromes.(5)     

Biology and systematics of heterokont and haptophyte algae

In this paper, I review what is currently known of phylogenetic relationships of heterokont and haptophyte algae. Heterokont algae are a monophyletic group that is classified into 17 classes and represents a diverse group of marine, freshwater, and terrestrial algae. Classes are distinguished by morphology, chloroplast pigments, ultrastructural features, and gene sequence data. Electron microscopy and molecular biology have contributed significantly to our understanding of their evolutionary relationships, but even today class relationships are poorly understood. Haptophyte algae are a second monophyletic group that consists of two classes of predominately marine phytoplankton. The closest relatives of the haptophytes are currently unknown, but recent evidence indicates they may be part of a large assemblage (chromalveolates) that includes heterokont algae and other stramenopiles, alveolates, and cryptophytes. Heterokont and haptophyte algae are important primary producers in aquatic habitats, and they are probably the primary carbon source for petroleum products (crude oil, natural gas).     

Hereditary stability and variation in evolution and development

Evolution and development are both lineage processes but are often conceptualized as occurring by different and mutually exclusive mechanisms. It is conventionally asserted that evolution occurs via the random generation of diversity and the subsequent survival of those that pass selection. On the other hand, development is too often presented as proceeding via the unfolding of a deterministic program encoded in the DNA sequence. In biology, universal generalizations are rare and dogmas are often wrong for particular cases. Deterministic mechanisms contribute some of the new DNA sequences that subsequently become substrates for natural selection. Conversely, stochastic and selective mechanisms are intrinsic to development, and also to maintenance of the immune, and possibly, nervous systems. Cancer appears to be another process that straddles distinctions between evolutionary and developmental modes of hereditary change and stabilization. DNA sequence changes are an essential feature of many cancers, but there are also aspects of the disease similar to developmental lineage gone awry. The literature suggests that the cellular changes that give rise to cancer occur by mechanisms commonly associated with both evolutionary and developmental lineage pathways.     

DNA polymerases β and λ and their roles in DNA replication and repair

DNA-dependent DNA polymerases are the main enzymes that catalyze DNA replication. Higher eukaryotic cells have 19 DNA polymerases with strikingly different properties [1]. Mitochondrial DNA polymerase γ of the A family and most of the nuclear enzymes of the B family are high-fidelity DNA polymerases that are involved not only in genomic DNA replication but also in DNA repair. Among the other 15 proteins, DNA polymerases belonging to the X and Y families have a special place. The majority of these enzymes are also involved in repair, including base excision repair and nonhomologous end joining. Some of them play a specific role in replication of damaged DNA templates. This process is referred to as translesion synthesis (TLS). DNA polymerases β and λ, which belong to the X structural family, are polyfunctional enzymes; their properties and functions are discussed.     

武陵山地区珍稀濒危植物及其保护利用

武陵山地区分布的国家级珍稀濒危植物共47种,隶属于26科42属,其中保护植物属国家一级的2种,二级的17种,三级的28种。对其种类组成、濒危等级现状、区系成分、地理分布及利用价值进行初步分析。结果表明,属濒危的种类3种,易危的20种,依赖保护的13种,需予关注的11种,武陵山地区珍稀濒危植物不仅有古老、原始、孑遗的特性,且亚热带性质明显,中国特有现象极为突出。水平分布可分为南、北两个中心,垂直分布以500~2000m的中山地带为主。武陵山地区的珍稀濒危植物除部分具一定直接经济价值外,多数都有重要的间接经济价值。据此提出武陵山地区珍稀濒危植物的保护利用对策。     

喀斯特石漠化地区野生饲用灌木、半灌木资源及其开发利用

喀斯特地区野生饲用灌木资源充裕,但有效的开发和利用比较滞后。通过深入挖掘喀斯特地区野生饲用灌木、半灌木资源及其利用价值,详细阐述了灌木、半灌木的营养、饲用、药用、生态价值,具体分析了野生饲用灌木、半灌木开发利用存在的问题及对策。     

Localization and organization of microfilaments and related proteins in normal and virus-transformed cells

The localization and organization of actin-like microfilaments in normal, SV-40 and adenovirus transformed cells are determined by the coordinated use of light optical, electron optical and biochemical techniques. In adenovirus-type 5 transformed hamster embryo cells, microfilament meshworks appear to be the predominant organizational form of cellular actin, while in normal hamster cells, microfilament bundles are prevalent. Differences between 3T3 and SV-40 transformed 3T3 cells are less apparent and may be related to the packing and intracellular distribution of microfilament bundles. Attempts at relating these ultrastructural changes in transformed cells to the images obtained following reaction with fluorescein-labelled myosin fragments and indirect immunofluorescence with smooth muscle myosin antibody are discussed. In several instances the fluorescence microscope images do not correspond to the ultrastructural observations. The results are discussed in terms of the possible relationships between alterations in cytoplasmic contractile elements and the abnormal behavior of transformed cells.     

植物种子贮藏蛋白质及其细胞内转运与加工

高等植物种子成熟过程中贮存大量的贮藏蛋白质作为种子发芽和初期生长的重要营养来源。根据溶解性不同, 种子贮藏蛋白质可分为白蛋白、球蛋白、醇溶蛋白和谷蛋白4类。在种子胚发育过程中, 醇溶蛋白在粗面内质网合成后形成蛋白质聚集体, 直接出芽形成蛋白体并贮存其中。白蛋白、球蛋白和谷蛋白在粗面内质网以分子量较大的前体形式合成后, 根据各自的分选信号进入特定的运输囊泡, 经由受体依赖型运输/聚集体形式运输转运至蛋白质贮藏型液泡中, 然后经过液泡加工酶等的剪切转换为成熟型贮藏蛋白质并贮存其中。蛋白质的合成、分选、转运和加工等过程影响种子蛋白质的品质及含量。该文对种子贮藏蛋白质的分类和运输、加工以及这些过程对种子蛋白质品质和含量的影响进行了概述。     

植物种子贮藏蛋白质及其细胞内转运与加工

高等植物种子成熟过程中贮存大量的贮藏蛋白质作为种子发芽和初期生长的重要营养来源。根据溶解性不同,种子贮藏蛋白质可分为白蛋白、球蛋白、醇溶蛋白和谷蛋白4类。在种子胚发育过程中,醇溶蛋白在粗面内质网合成后形成蛋白质聚集体,直接出芽形成蛋白体并贮存其中。白蛋白、球蛋白和谷蛋白在粗面内质网以分子量较大的前体形式合成后,根据各自的分选信号进入特定的运输囊泡,经由受体依赖型运输/聚集体形式运输转运至蛋白质贮藏型液泡中,然后经过液泡加工酶等的剪切转换为成熟型贮藏蛋白质并贮存其中。蛋白质的合成、分选、转运和加工等过程影响种子蛋白质的品质及含量。该文对种子贮藏蛋白质的分类和运输、加工以及这些过程对种子蛋白质品质和含量的影响进行了概述。     

Respiration and sleep

Some of the main aspects of the relations which exist between sleep and respiratory function are discussed. Physiological data obtained both in humans and in animals are analyzed. Some results obtained in normal healthy newborns are mentioned. The sleep related respiratory diseases are not evoked here.     

Glycosylation and lectins-examples of immunesurveillance and immune evasion

Cell surface proteins are posttranslationally modified by tightly regulated enzymes of glycosylation. Typical patterns of glycosylation may signal pathological situations to the immune system. Here, carbohydrate receptors on the surface of cells in the immune system are involved in regulation of effector cells. Moreover, some lectins are circulating in the plasma and take part in host defense. The code of carbohydrate modifications is impaired in malignant cells and yet they are not eliminated. In this review, we focus on recent experimental evidence for regulatory functions of lectins and carbohydrate derivatives in the immune system and tumours.     

Plant calcium signaling and monitoring: pros and cons and recent experimental approaches

Summary This review focusses on Ca²⁺-mediated plant cell signaling and optical methods for in vivo [Ca²⁺] monitoring and imaging in plants. The cytosolic free calcium concentration has long been considered the central cellular key in plants. However, more and more data are turning up that critically question this view. Conflicting arguments show that there are still many open questions. One conclusion is that the cytosolic free Ca²⁺ concentration is just one of many cellular network parameters orchestrating complex cellular signaling. Novel experimental strategies which unveil interference of cellular parameters and communication of transduction pathways are required to understand this network. To date only optical methods are able to provide both kinetic and spatial information about cellular key parameters simultaneously. Focussing on calcium there are currently three classes of calcium indicators employed (i.e., chemical fluorescent dyes, luminescent indicators, and green-fluorescent-protein-based indicators). Properties and capabilities as well as advantages and disadvantages of these indicators when used in plant systems are discussed. Finally, general experimental strategies are mentioned which are able to answer open questions raised here.Abbreviations CTZ coelenterazine - GFP green-fluorescent protein - FRET fluorescence resonance energy transfer - [Ca²⁺] calcium ion concentration - CaM calmodulin - CDPKs calmodulindomain protein kinases - IP₃ inositol 1,4,5-trisphosphate     

Anatomical and molecular systematics of Asteliaceae and Hypoxidaceae

The astelioid group of asparagoid lilies (Lilianae - Asparagales) comprises Hypoxidaceae, Asteliaceae, Blandfordia and Lanaria. New information is presented on astelioid anatomy, together with a review of other systematic characters. These data are analysed in the context of recent evidence from rbc L nucleotide sequences that astelioids are related to orchids, and that astelioids and orchids (plus Alania and Borya ) form a clade that is sister to all other asparagoid taxa. Hypoxidaceae and Asteliaceae differ from each other in several respects, but there are certain characters linking the two families, notably branched hairs and mucilage canals, unusual characters in Lilianae. Family diagnoses are upheld, but the precise relationships of Blandfordia and Lanaria are still poorly supported within the astelioid clade.     

Genetic and biochemical mechanisms of ontogenetic and phylogenetic adaptation

Results of the scientific research of genetic mechanisms of ontogenetic and phylogenetic adaptation in the department of genetics and molecular biology of the Odessa national university (ONU) are summarized. The new concept of genetic adaptation and adaptive heterosis is proposed. The evidence are presented that not only selection of selectively valuable alleles of the structural genes of enzymes, but also of gene-modifiers of the gene products are involved in the adaptation of D. melanogaster populations to environmental conditions. As a result, the sets of coadaptation alleles--adaptation complexes of genes (ACG), which are specific to the selective factors, are formed in persons of the population.     

Pterin transport and metabolism in Leishmania and related trypanosomatid parasites

The folate metabolic pathway has been exploited successfully for the development of antimicrobial and antineoplasic agents. Inhibitors of this pathway, however, are not useful against Leishmania and other trypanosomatids. Work on the mechanism of methotrexate resistance in Leishmania has dramatically increased our understanding of folate and pterin metabolism in this organism. The metabolic and cellular functions of the reduced form of folates and pterins are beginning to be established and this work has led to several unexpected findings. Moreover, the currently ongoing sequencing efforts on trypanosomatid genomes are suggesting the presence of several gene products that are likely to require folates and pterins. A number of the properties of folate and pterin metabolism are unique suggesting that these pathways are valid and worthwhile targets for drug development.