Lysosomal carboxypeptidase B from rabbit lung purification and characterization

Lysosomal carboxypeptidase B has been purified from rabbit lung acetone powder by acid precipitation and ammonium sulfate fractionation followed by further purification on Sephadex G-100, DEAE-Sephadex, Organomercurial-Sepharose, preparative isoelectric focusing, Sephadex G-75, and carboxymethyl-Sephadex. This procedure resulted in a homogeneous preparation as determined by polyacrylamide gel electrophoresis at pH 4.5, 8.3 and with sodium dodecyl sulfate. This enzyme has a molecular weight of 52,000, is composed of two subunits of approximately equivalent molecular weight, and is a glycoprotein with a carbohydrate content estimated to be 10% by weight. The amino acid composition is also reported. The enzyme is active on two synthetic substrates, α-N-benyoyl-l-arginineamide and hippuryl-l-arginine. With these two substrates, respectively, lysosomal carboxypeptidase B has pH optima of 5.7 and 5.0, temperature optima of 40 and 50 °C, and K_m values of 10 and 16 mm. With each substrate, the enzyme requires the presence of a reducing agent for maximal activity and is inhibited to the same extent with several inhibitors. The most potent inhibitors were leupeptin and antipain at low concentrations (1 μm). Iodoacetate and Ac-(Ala)₃-Ala-chloro-methyl ketone also inhibited at higher concentrations (10 μm). However, compounds such as leucyl-chloromethyl ketone, bestatin, pepstatin, phenylmethylsulfonyl fluoride, soybean trypsin inhibitor, and α-1-antitrypsin did not inhibit. When tested with peptides as substrates, this proteinase exhibited strong carboxypeptidase activity on the tetrapeptide, ThrProArgLys, and on angiotensin I, AspArgValTyrIle HisProPheHisLeu, liberating Lys, and Leu, respectively. Substance P (containing 11 amino acids plus a C-terminal amide group) was virtually inactive as a substrate for this enzyme. However, with oxidized insulin B chain as substrate, lysosomal carboxypeptidase B exhibited significant carboxypeptidase and endopeptidase activities.     

The relationship of age,sex, and reproductive state to assimilation efficiency in the adult milkweed bug, Oncopeltus fasciatus

The influence of age, sex, and reproductive state on efficiency of assimilation was examined in the milkweed bug Oncopeltus fasciatus. Amounts of food ingested and excreted decline with age in virgin males and females. Mated females laying eggs ingest significantly more food than virgin animals of either sex and also maintain a consistently higher assimilation efficiency. A qualitative analysis of the level of assimilation required for reproductive effort is discussed.     

Stability constants of metal complexes of phosphonoacetic acid

The antiviral drug, phosphonoacetic acid (PAA), forms stable complexes with Mg²⁺, Ca²⁺, Cu²⁺ and Zn²⁺. Stability constants of these complexes were determined in aqueous solution (0.15 M in KNO₃, 37°) by potentiometric titration. Mixed ligand complex formation of Cu²⁺ and Zn²⁺ with PAA and glycinate ion, and with PAA and histidinate ion, was studied. In a theoretical model for blood plasma, PAA affects the distribution of Mg²⁺ and, to a lesser extent, Ca²⁺.     

Axon initiation by ciliary neurons in culture

A nerve culture system for the study of axon initiation is described. A population of individual chick embryo ciliary neurons, free from contact with other cells and attached to a polyornithinecoated culture dish, is exposed to heart cell-conditioned medium (HCM). Within 30 min after the addition of HCM the majority of neurons have formed growth cones, and by 90 min more than 80% of the neurons bear at least one axon longer than 15 μm. Before the addition of HCM, ciliary neurons generate membrane ruffles and extend filopodia around the entire periphery of the rounded cell body. Axon initiation, following addition of HCM, consists of two distinctive changes in the cell surface: (1) organization of the randomly distributed surface movements into localized highly active growth cones, which then form axons; and (2) the cessation of surface movements elsewhere on the cell periphery. Heart cell-conditioned medium may induce these changes by increasing the adhesion between parts of the nerve cell surface and the substratum.     

Studies of the lungs in diabetes mellitus. II. Phospholipid analyses on the surfactant from broncho-alveolar lavage fluid of alloxan-induced diabetic rats

Structurally diverse anions (folate, 5-formyltetrahydrofolate, AMP, ADP, thiamine pyrophosphate, phosphate, sulfate, and chloride) that are competitive inhibitors of methotrexate influx in L1210 cells also enhance the efflux of methotrexate from these cells. The increase in efflux reaches a maximum of 2- to 4-fold depending upon the anion employed, and the anion concentrations required for half-maximal stimulation of efflux are similar to their K_i values for inhibition of methotrexate influx. A competitive inhibitor of methotrexate uptake (fluorescein-diaminopentane-methotrexate) that is not transported by this system, does not increase methotrexate efflux. These results suggest that the efflux of intracellular methotrexate is coupled to the concomitant uptake of an extracellular anion.     

Identifying the methodological characteristics of European green city rankings

City rankings that aim to measure the environmental sustainability of European cities may contribute to the evaluation and development of environmental policy of European cities. The objective of this study is to identify and evaluate the methodological characteristics of these city rankings. First, a methodology was developed to systematically identify methodological characteristics of city rankings within different steps of the ranking development process. Second, six city rankings (European Energy Award, European Green Capital Award, European Green City Index, European Soot-free City Ranking, RES Champions League, Urban Ecosystem Europe) were examined. Official websites and any methodological documents found on those websites were content analyzed using the developed methodology. Interviews with representatives of the city rankings were conducted to acquire any additional information. Results showed that the city rankings varied greatly with respect to their methodological characteristics and that all city rankings had methodological weaknesses. Developers of city rankings are advised to use the methodology developed in this study to find methodological weaknesses and improve their ranking. In addition, developers ought to be more transparent about the methodological characteristics of their city rankings. End-users of city rankings are advised to use the developed methodology to identify and evaluate the methodological characteristics of city rankings before deciding to act on ranking results.     

A new analytical method for wildlife habitat conservation planning on a city scale using the classification of physiologically homogeneous areas

Kyoto has a tradition of positively protecting scenic landscapes. However, a question has arisen about the effectiveness of the present legislative system on biodiversity conservation because most laws aim to essentially preserve the aesthetic value of the landscape. It is necessary to identify gaps in the present conservation system to develop an effective conservation policy for the city. The authors propose a practical method of analysis for wildlife habitat conservation planning without wildlife distribution information, which is the usual situation in many cities, and discuss the usefulness and limitations of the method by applying it to Kyoto. The proposed method relies on both of the following two assumptions: (1) the physical properties of the environment are closely related to the potential vegetation communities and (2) the conservation or restoration of rare or extinct vegetation communities ensures diverse wildlife habitats, contributing to biodiversity enhancement in a region. Thus it should be deemed a supplementary analysis to other types of analyses employing endangered, umbrella and/or flagship species in the planning process. A unique aspect of the method is to evaluate land potential, which is important for long-term conservation planning and the determination of target vegetation communities in restoration projects. In Kyoto, this revealed that the candidates for vegetation communities, prioritized for conservation and restoration, were appropriate. Moreover, identifying physiotopes corresponding with none of the existing vegetation communities was another advantage providing useful information for restoration planning. However, it was considered that a filtering process, with auxiliary information about the trend of vegetation communities over time, was necessary after applying the proposed method.     

深圳塘朗山郊野公园的植物资源

广东深圳塘朗山郊野公园共有野生维管植物144科423属611种,分别占广东省维管植物280科1589属5737种的51.4%、26.7%和10.65%;其中蕨类省植物21科29属33种,裸子植物3科3属4种,被子植物120科391属574种,被子植物占绝对优势。国家重点保护野生植物共计7科7属7种,占广东省国家重点保护野生植物的10.9%;珍稀濒危植物有4科5属5种,占广东省珍稀濒危植物67种的7%。公园中经济植物可分为12类,分别是药用植物321种,用材树种65种,观赏植物60种,纤维植物41种,野生水果33种,油脂植物38种,饲料植物42种,鞣料植物42种,野菜植物25种,农药植物27种,芳香植物26种,淀粉植物23种,保健植物19种,染料植物13种,有毒植物10种,蜜源植物5种。     

Resource exploitation of larvae ofGastrophysa atrocyanea Motschulsky andgalerucella vittaticollis Baly (Coleoptera: Chrisomelidae) under a limited resource condition

Resource exploitation by and intraspecific competition in larvae of Gastrophysa atrocyanea and Galerucella vittaticollis were investigated in field and laboratory experiments. Larvae of both species frequently suffered from food shortages in the field. When G. atrocyanea larvae suffered from a food shortage, severe intraspecific competition occurred because of lack of predation and parasitism. This exploitive competition was caused by a local food shortage of the host plant. Individuals survived by fast exploitation when food became abundant (contest type competition). the G. atrocyanea larvae were wasteful of the food resource, and no mechanism by which to economize on the utilization of the resource was acquired because of their exploitation of the abundant resource. In contrast, the G. vittaticollis population probably is regulated by extrinsic factors such as predation and parasitism. Those larvae grew into smaller adults than those of G. atrocyanea under a food shortage, so that their wasted food consumption was lower than that of G. atrocyanea. Although intraspecific competition was similar to that for G. atrocyanea, it was not as severe. The food for G. vittaticollis was apt to be appropriated by other wasteful exploitators such as G. atrocyanea, which was superior in resource exploitation; therefore G. vittaticollis frequently suffered a food shortage. Consequently selection in relation to tolerance to starvation became more acute for G. vittaticollis than for G. atrocyanea, and individuals of G. vittaticollis that could endure starvation better may have been selected.