Cell wall alterations in staphylococci growing in situ in experimental osteomyelitis

When cells of both Staphylococcus aureus and Staphylococcus epidermidis are grown in batch culture in nutrient-rich media, their cell walls are regular in thickness, their cell size is within the normal range for each species, and their septation patterns are orderly. When cells of each of these species are examined directly in infected tissue in the rabbit tibia model infection, their cell wall thickness is often much increased and very irregular around the circumference of the cell, their cell size is often increased, and their septation patterns are often severely deranged. All of these alterations in cell wall structure occur in the absence of antibiotics, and we suggest that they may be an expression of phenotypic plasticity in response to altered environmental conditions such as specific nutrient limitations, the presence of antibacterial factors, and growth of the cells on hard surfaces such as rabbit bone or plastic catheters. Some of these specific cell wall alterations are also seen when staphylococcal cells are exposed, in vitro or in vivo, to antibiotics such as clindamycin, but we emphasize that growth in tissue alone is sufficient for their induction.     

Strong patterns in homooligomer tracts occurrences in non-coding and in potential regulatory sites in eukaryotic genomes

Previous studies of the dinucleotides flanking both the 5' and 3' ends of homooligomer tracts have shown that some flanks are consistently preferred over others (1,2). In the first preferred group, the homooligomer tracts are flanked by the same nucleotide and/or the complementary nucleotides, e.g.,ATAn,TTAn,CCGn, where n = 2-5. Runs flanked by nucleotides with which they cannot base pair are distinctly disfavored. (In this group An/Tn are flanked by C and/or G; Gn/Cn are flanked by A/T, e.g.,CGAn,TnGG,GnAT). The frequencies of runs flanked by A or T, and G or C ("mixed"group) are as expected. Here we seek the origin of this effect and its relevance to protein-DNA interactions. Surprisingly, within the first group, runs flanked by their complements with a pyrimidine-purine junction (e.g.,TTAn,CnGG) are greatly preferred. The frequencies of their purine-pyrimidine junction mirror-images is just as expected. This effect, as well as additional ones enumerated below, is seen universally in eukaryotes and in prokaryotes, although it is stronger in the former. Detailed analysis of regulatory regions shows these strong trends, particularly in GC sequences. The potential relationship to DNA conformation and DNA-protein interaction is discussed.     

Dogs and Cats in Animal Shelters in Japan

ABSTRACT

Although there are proportionately fewer pet owners in Japan than in the United States, the keeping of indigenous Japanese dog breeds, along with those common in Europe and North America, is long-established. Japan has a centralized governmental network of animal shelters, which permits accurate record-keeping of the numbers of dogs and cats admitted, reclaimed, and euthanized. Although in the United States an accurate census is not simple to accomplish because a variety of humane societies and animal control agencies admit homeless dogs and cats, some cultural comparisons are possible.

Despite recent increases in petkeeping in Japan, the numbers of dogs admitted to shelters have decreased from 345,136 dogs in 1984 to 243, 753 dogs in 1994. The numbers euthanized show similar declines, from 331,442 in 1984 to 219,831 in 1994. In the city of Tokyo, kittens account for the majority of the animals admitted: 34,745 kittens (55%) of a total of 62,803 dogs and cats in 1980; 12,805 kittens (61%) of a total of 21,075 in 1993. Cats usually are brought in after being found on the street and are not reclaimed by their owners; virtually all are euthanized. Most dogs, 61%, are caught as strays by shelter personnel. Among those admitted to Tokyo shelters, 41% are reclaimed or returned to the owner, 7% are adopted by new owners, and 52% are euthanized.

Spaying and neutering of dogs and cats are not wide spread practices in Japan. There are few private shelters; the government provides no tax incentives for charitable contributions to such organizations. While American shelters invariably offer animals for adoption, most of Japan's governmental shelters do not. However, this is gradually changing.     

细根分解研究及其存在的问题

细根分解是陆地生态系统C和养分循环的重要环节。主要包括淋溶和破碎等物理过程和以生物作用为主的化学过程。这些过程受复杂的细根化学成分及外部土壤因子的综合控制,如细根本身养分含量、木质素和纤维素含量、土壤温度、水分、养分的有效性以及土壤动物、真菌和细菌等。但是,细根分解发生在不能直接观测的地下部分,人为改变细根分解的自然环境是研究过程中存在的主要问题。埋袋法虽然应用最为普遍,但是它严重地干扰了细根分解环境,导致低估分解速率。最近提出的原状土芯法(intact-core)克服了埋袋法的主要缺陷,是目前细根分解研究中最接近自然分解过程的研究方法,但也存在一些问题。因此,如何设计有效且能够真实的反映细根自然分解过程的试验方法是今后该领域研究最重要和最具挑战性的课题。     

Cofactor Regeneration in Biocatalysis in Organic Media

Methods used for the regeneration of cofactors in organic media are reviewed. Substratedriven regeneration methods include the use of a second substrate of the same enzyme and the use of a second enzyme and its substrate. The use of mediators in oxidoreductions is described and examples of photochemical and electrochemical regeneration methods are presented. General problems and possibilities of cofactor regeneration in organic media are discussed.     

浙江凤阳山-百山祖自然保护区蕨类植物区系研究

通过对凤阳山--百山祖自然保护区蕨类植物野外资源调查及区系分析,可以认为,凤阳山--百山祖保护区共有蕨类植物39科、79属、249种(含变种),主要科为鳞毛蕨科、水龙骨科、金星蕨科、蹄盖蕨科和膜蕨科;主要属为鳞毛蕨属、复叶耳蕨属、铁角蕨属、蹄盖蕨属和瓦韦属,其中以鳞毛蕨属和复叶耳蕨属分布相对集中。属的分布类型以热带成分为主,种以东亚分布类型和中国特有种为主,并含有72种中国特有和珍稀蕨类植物。     

Human schistosomiasis in wetlands in southern Africa

This review describes the types of habitats in which human schistosomiasis is transmitted in wetlands across southern Africa. The snails that serve as the parasites?? intermediate hosts are tolerant of water with a wide range of chemical composition but are restricted by current velocity, temperature and habitat permanence. Human contact with the water in snail habitats is crucial to the establishment of transmission and children are more frequently and more severely infected than adults. Swimming is the contact activity that contributes most to transmission. Case studies illustrating the roles of high temperatures, hydrology and over-fishing in the epidemiology of the disease in the region are also reviewed.     

Biomarkers discovery in cancer--up-dates in methodology

Biomarkers are biomolecules that can indicate normal/pathological processes, or physiological responses to therapy. Due to the serum abundance in proteins, such as albumin and lypo/glycoproteins, biomarkers are difficult to assess. Serum biomarkers identification can contribute to personalized medicine and improve cancer diagnostic and prognostic. The paper summarizes some of the proteomics techniques and the workflow used for protein signatures identification associated to cancer development. Thus, biomarkers validated for prostatic, breast, cervical or lung cancers are presented as examples for clinical application of serum markers. In spite of the continuous research efforts, there are only few validated biomarkers that have proved a good predictive power in cancer. Modern technology and the combination of various techniques used for proteins quantification represent important means for the identification and validation of new biomarkers.     

The Formation of Pollen Dimorphism in Paris axialis in Vivo

It is obsreved that the dimorphic populations of pollen are producedin Paris axialis H. Li In vivo. The normal pollen grains and abnormal pollen grainsare 77.1% and 22.9% respectively; more than 70% of abnormal pollen grains conformto the equal nucleus type. The abnormal pollen grains show no delayed development,and thay are stained as dark as the normal ones. During the first mitotic division of microspore, most of the spindles are anticlinal(perpendicular to the intine), the cytokinesis is generally asymmetric, and a completewall is formed. However, a few mitotic spindles of mitotic microspores are periclinal,and the cytokinesis are symmetric. Sometimes a partial wall is observed between twodaughter nuclei, which are produced by the abnormal pollen grains. We believe thatthese phenomena are related to differentiation of the dimorphic pollen.     

Leptofibrils in rat ventricular cardiomyocytes in vitro

The presence of leptofibrils in ventricular myocytes of the heart of the 2- and 14-day old rats in 8-day old cultures was shown and their structure was investigated. Leptofibrils are seen only in myocytes on a definite stage of differentiation. Leptofibrils are attached to Z-bands running parallel or perpendicular to myofibrils. The period of their cross striation varies from 135 to 215 nm. Possible functions of the leptofibrils are discussed.     

Subunits in zonulae adhaerentes and striations in the associated circumferential microfilament bundles in chicken retinal pigment epithelial cells in situ

This study shows that the zonula adhaerens in chicken retinal pigment epithelial (RPE) cells in situ consists of independent subunits which are composed of extracellular intermembrane discs sandwiched between cytoplasmic plaques. These zonula adhaerens complexes (ZACs) are hexagonally arranged within the junction. Previous immunocytochemical studies suggest that the zonula adhaerens region, composed of ZACs, contains the actin associated proteins vinculin and alpha-actinin. The intermembrane discs of ZACs likely mediate cell-to-cell adhesion whereas the cytoplasmic plaques are probably involved in binding the microfilaments of the relatively large circumferential microfilament bundles (CMBs), associated with the zonula adhaerens, to the cell membrane. The CMBs of chicken RPE cells in situ show striations similar to those found in stress fibers of other cell types and in CMBs of cultured epithelial cells. The observation that in the striated regions of CMBs the adjacent junctional membranes tend to follow an undulating path suggests that the CMBs are attached intermittently to the cell membrane and are contractile. The structural similarities between CMBs and stress fibers and the fact that they share similar actin associated proteins support the view that CMBs and stress fibers are related structures.     

细菌群体感应LuxR solos蛋白研究进展

N-酰基高丝氨酸内酯(N-acyl-L-homoserine lactones,AHLs)信号分子介导的群体感应(quorum sensing,QS)是一种普遍的革兰氏阴性细菌信息交流方式。AHL-QS系统包括Lux I型AHLs合成酶和LuxR型受体蛋白。然而,部分革兰氏阴性菌缺失1个或多个LuxI型AHLs合成酶,仅有未配对的LuxR型受体蛋白,该LuxR型受体蛋白称为LuxR solo或Orphan蛋白。LuxR solos蛋白在细菌窃听、种间和种内的信号交流中起重要作用,为群体感应研究领域的热点。本文主要综述细菌LuxR solos蛋白的发现、基本概念、蛋白结构及类型,阐述感应AHLs和非AHLs信号分子的重要LuxR solos蛋白及功能,并对群体感应LuxR solos蛋白的研究前景和意义进行了展望。     

Role of microbial enzymes in flavor development in foods

There are four main sources of enzymes in foods—these being the inherent enzymes, enzymes from microbial contaminants, enzymes elaborated by microorganisms added to foods, and specific enzymes added to foods. This study primarily deals with the latter two sources of enzymes in food. Although both plants and animals serve as sources of enzymes, they are not as economical or versatile sources as are enzymes obtained from microorganisms. In the meat industry, proteases are used to tenderize muscle and to obtain flavor precursors. In the preparation of cured meat products such as sausages, lipases, and proteases from bacterial cultures are utilized. Similarly, proteases and lipases are used in the dairy industry to develop flavor compounds. Proteases and amylases also have applications in the baking and milling industries where they are used to produce precursors for the nonenzymatic browning reactions. Carbohydrases such as amylase, amyloglucosidase, and glucose isomerase have found usage in the starch and syrup industry for the production of high dextrose and high fructose syrups. Other enzymes such as glucose oxidase, pectinase, and naringinase are of value to the wine and fruit juice industries. A better understanding of the mode of action of enzymes as well as the mechanisms of development of flavor compounds will further enhance the use of microbial enzymes to develop specific and desired flavors in foods.     

植物体中的MAPK

促细胞分裂剂激活性蛋白激酶（MAPK）是一类存在于各种真核生物体中的丝氨酸/苏氨酸型蛋白激酶。它被上游激活因子MAPKK磷酸化而激活,并通过将底物蛋白上的丝氨酸和苏氨酸残基磷酸化而传递信号。它与其他一些信号分子组成MAPK级联信号通路,接受外界刺激信号,将信号转入细胞内,影响特定基因的表达,它的作用受到不同因子的调节。本文介绍了植物体中的MAPK的结构特点、作用机理、生物功能以及MAPK级联信号通路的调节。     

参与植物细胞壁半纤维素木聚糖合成的糖基转移酶

木聚糖是双子叶植物次生细胞壁中最主要的半纤维素,含有木聚糖的次生壁是最丰富的植物生物质,广泛应用于能源、制浆、造纸和纺织业中,但其主要组分戊糖对细胞壁生物质利用具有较大影响。揭示木聚糖合成的分子机制,为遗传修饰细胞壁组成,更好地利用细胞壁生物质提供新的策略。近年来对模式植物拟南芥中多个木聚糖合成有缺陷的突变体的分析表明：GT43家族的IRX9、IRX9-L、IRX14、IRX14-L,GT47家族的FRA8、F8H、IRX10、IRX10-L,GT8家族的IRX8、PARVUS、QUA1、GUX1、GUX2等参与了木聚糖主链、还原末端序列和侧链的合成。本文主要对这些研究进展做一综述,并讨论了木聚糖合成的机制及亟待解决的问题,展望了其发展趋势。     

Extreme bias in sex allocation in Eclectus parrots

We investigated extraordinary patterns of sex allocation in captive eclectus parrots (Eclectus roratus). These birds are extremely unusual as they show reverse sexual dichromatism, they are the only cooperatively breeding parrot, and they are one of the few birds with nestlings that are easily sexed. They lay two eggs per clutch, but often only fledge one young, and the sex ratio of 209 fledglings did not differ significantly from parity. However, when two young are fledged together they are very likely to be of the same sex, and some females produce long unbroken runs of one sex (the maximum was 20 males) before switching to the other sex. Monte-Carlo simulations show that these runs of same-sex clutches defy expectation if we assume that the sex of chicks within each clutch is independent of the previous clutch. We use further simulations to show that the sex bias must occur at fertilization (i.e. the primary sex ratio), although the female may make further adjustments via infanticide. Control over sex allocation in eclectus parrots is one of the most extreme reported from birds.     

Proteinoid microspheres more stable in hot than in cold water

The occurrence of organisms of primitive appearance near submarine hydrothermal vents has indicated sea-floor conditions that are like those under which proteinoid microspheres are produced in the laboratory. Experimental examination of the question of whether some proteinoid microspheres might be stable in hot water has revealed proteinoids that are soluble in cold water but precipitate on heating. Unanswered questions are discussed.     

Enzymology of DNA in replication in prokaryotes

This review stresses recent developments in the in vitro study of DNA replication in prokaryotes. New insights into the enzymological mechanisms of initiation and elongation of leading and lagging strand DNA synthesis in ongoing studies are emphasized. Data from newly developed systems, such as those replicating oriC containing DNA or which are dependent on the lambda, O, and P proteins, are presented and the information compared to existing mechanisms. Evidence bearing on the coupling of DNA synthesis on both parental strands through protein-protein interactions and on the turnover of the elongation systems are analyzed. The structure of replication origins, and how their tertiary structure affects recognition and interaction with the various replication proteins is discussed.     

Changes in thick filament length in Limulus striated muscle

Here we describe the change in thick filament length in striated muscle of Limulus, the horseshoe crab. Long thick filaments (4.0 microns) are isolated from living, unstimulated Limulus striated muscle while those isolated from either electrically or K+-stimulated fibers are significantly shorter (3.1 microns) (P less than 0.001). Filaments isolated from muscle glycerinated at long sarcomere lengths are long (4.4 microns) while those isolated from muscle glycerinated at short sarcomere lengths are short (2.9 microns) and the difference is significant (P less than 0.001). Thin filaments are 2.4 microns in length. The shortening of thick filaments is related to the wide range of sarcomere lengths exhibited by Limulus telson striated muscle.     

Strong Patterns in Homooligomer Tracts Occurrences in Non-Coding and in Potential Regulatory Sites in Eukaryotic Genomes

Abstract

Previous studies of the dinucleotides flanking both the 5′ and 3′ ends of homooligomer tracts have shown that some flanks are consistently preferred over others (1,2). In the first preferred group, the homooligomer tracts are flanked by the same nucleotide and/or the complementary nucleotides, e.g., ATA_n, TTA_n, CCG_n, where n=2–5. Runs flanked by nucleotides with which they cannot base pair are distinctly disfavored. (In this group A/T_n are flanked by C and/or G; G_n/C_n are flanked by A/T, e.g., CGA_n, T_nGG, G., AT). The frequencies of runs flanked by AorT, and G or C (“mixed” group) are as expected. Here we seek the origin of this effect and its relevance to protein-DNA interactions. Surprisingly, within the first group, runs flanked by their complements with a pyrimidine-purine junction (e.g., TTA_n, C_nGG) are greatly preferred. The frequencies of their purine-pyrimidine junction mirror-images is just as expected. This effect, as well as additional ones enumerated below, is seen universally in eukaryotes and in prokaryotes, although it is stronger in the former. Detailed analysis of regulatory regions shows these strong trends, particularly in GC sequences. The potential relationship to DNA conformation and DNA-protein interaction is discussed.