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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of temperature over 8 time intervals on survival of cleavage stages, trochophore larvae, and straighthinge veliger larvae of Mulinia lateralis (Say) was investigated using a thermal gradient apparatus. There was a direct relationship of mortality with increased period of exposure. As the clams aged, temperature tolerance increased, with cleavage stages being most sensitive to higher temperatures and straight-hinge larvae least sensitive. Multiple-regression equations were developed to allow prediction of percentage mortalities under different conditions of temperature and time exposure. Entrainment of M. lateralis embryos and larvae in the cooling-water systems of steam-electric power plants should be as short as possible to keep mortality toa minimum.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The action of various concentrations of zinc on different phases of development of Arbacia lixula L. has been observed. The following concentrations were used in the experiment: 0.01, 0.1, 1 and 10 mg l-1; these concentrations were tested on unfertilized eggs, sperms, fertilized eggs and adult individuals. It was found that after 96 h a 0.01 mg l-1 concentration reduces the mobile sperm percentage compared with the control group. At concentrations of 0.1, 1 and 10 mg l-1 no mobile sperm were found after 96 h. Compared with the control group, the action of zinc on unfertilized eggs was to increase the percentage of eggs showing signs of cytolisis after 12, 36 and 60 h. In the case of fertilized eggs it was found that with a concentration of 0.01 mg l-1 the P5 pluteus stage was attainable; the percentage of forms reaching that stage was less than in the control group. At 0.1 mg l-1 only a very low percentage of eggs could reach the P5 pluteus stage; concentrations of 1 and 10 mg l-1 are incompatible with the normal development of an egg. Adult individuals kept in aquaria with 1 mg l-1 zinc showed no signs of suffering after 20 d. Gametes are proposed as the appropriate material for carrying out bioassays.
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  • 3
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thermal tolerance studies on three larval stages of five species of bivalve are compared: Crassostrea virginica, Mulinia lateralis, Argopecten irradians, Mercenaria mercenaria, and Spisula solidissima. Experiments were designed to simulate possible larval entrainment in the cooling systems of power plants and involved an 11 (temperature)x8(time-exposure) experimental matrix. Temperatures ranged from about 17.4° to 43°C at approximately 2C° intervals, and exposure times ranged from 1 min to 6 h (sometimes longer in the case of C. virginica). For all species, larval mortality generally increased with increasing exposure temperature and with increased time-exposure at any one temperature. In some species (M. mercenaria and A. irradians), a cold-shock was also apparent (i.e. increased mortality at temperatures below those at which the larvae were spawned). In the case of A. irradians, this effect was more noticeable at the trochophore stage than at the other two stages, although for all species investigated, there was a general trend of decreased thermal sensitivity with increasing age. Despite some interspecies variability from temperature to temperature and from stage to stage, S. solidissima was the most sensitive species and A. irradians was intermediate in thermal tolerance between this and the other three species. At temperatures as high as 40°–41°C, straight hinge M. mercenaria and C. virginica sustained low mortality for more than 2 h and on this basis were judged to be the most “temperature-shock” resistant of all larvae investigated. However, younger stages showed no significant differences between M. mercenaria, C. virginica or M. lateralis, and we conclude that these three species are generally very similar in their larval resistance to thermal increase. All three are more euryhaline than are the remaining two polyhaline or marine species.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 174 (2000), S. 213-224 
    ISSN: 1432-1424
    Keywords: Key words: Amino acid transport — Cotransport — KAAT1 — Inhibition —Xenopus laevis oocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. When expressed in Xenopus oocytes KAAT1 increases tenfold the transport of l-leucine. Substitution of NaCl with 100 mm LiCl, RbCl or KCl allows a reduced but significant activation of l-leucine uptakes. Chloride-dependence is not strict since other pseudohalide anions such as thyocyanate are accepted. KAAT1 is highly sensitive to pH. It can transport l-leucine at pH 5.5 and 8, but the maximum uptake has been observed at pH 10, near to the physiological pH value, when amino and carboxylic groups are both deprotonated. The pH value mainly influences the V max in Na+ activation curves and l-leucine kinetics. The kinetic parameters are K mNa = 4.6 ± 2 mm, V maxNa = 14.8 ± 1.7 pmol/oocyte/5 min for pH 8.0 and K mNa = 2.8 ± 0.7 mm, V maxNa = 31.3 ± 1.9 pmol/oocyte/5 min for pH 10.0. The kinetic parameters of l-leucine uptake are: K m = 120.4 ± 24.2 μm, V max = 23.2 ± 1.4 pmol/oocyte/5 min at pH 8.0 and K m = 81.3 ± 24.2 μm, V max = 65.6 ± 3.9 pmol/oocyte/5 min at pH 10.0. On the basis of inhibition experiments, the structural features required for KAAT1 substrates are: (i) a carboxylic group, (ii) an unsubstituted α-amino group, (iii) the side chain is unnecessary, if present it should be uncharged regardless of length and ramification.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Formal aspects of computing 8 (1996), S. 247-293 
    ISSN: 1433-299X
    Keywords: Type theory ; Typed foundation of object-oriented programming ; Second order λ-calculus ; Bounded polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In this paper we define an extension ofF ≤ [CUG92] to which we add functions that dispatch on different terms according to the type they receive as argument. In other words, we enrich the explicit parametric polymorphism ofF ≤ by an explicit “ad hoc” polymorphism (according the classification of [Str67]). We prove that the calculus we obtain, calledF ≤ & , enjoys the properties of Church-Rosser and Subject Reduction and that its proof system is coherent. We also define a significant subcalculus for which the subtyping is decidable. This extension has not only a logical interest but it is strongly motivated by the foundation of a broadly used programming style: object-oriented programming. The connections betweenF ≤ & and object-oriented languages are widely stressed, and the modelling byF ≤ & of some features of the object-oriented style is described, continuing the work of [CGL96].
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 88 (1994), S. 818-823 
    ISSN: 1432-2242
    Keywords: Diploid wheat ; Einkorn ; RFLP ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To study the relationships between different species of the Einkorn group, 55 different accessions ofTriticum monococcum,T. boeoticum,T. urartu,T. sinskajae,T. thaoudar andT. aegilopoides were analyzed. Fifteen anonymous probes and four clones corresponding to storage protein genes were used for detecting restriction fragment length polymorphisms (RFLPs). The DNA was restricted with the restriction enzymesAluI,HaeIII,RsaI andTaqI. The 25 probe/enzyme combinations employed yielded a total of 488 polymorphic fragments. Statistical analyses were performed using Jaccard's coefficient of similarity and principal coordinate analysis. Different values of similarity within the three main taxa,monococcum,boeoticum andurartu, were obtained; the grouping at the species level was quite well reflected by the RFLP analysis done here. The coincidence between RFLP data and the subspecies classification of theT. monococcum group was only partial. OneT. urartu accession is clearly different from all of the other 54 accessions. The need for an RFLP based revision of the Einkorn taxonomy is evident.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 94 (1997), S. 424-430 
    ISSN: 1432-2242
    Keywords: Key words Triticum urartu ; Wheat ; A genome ; RFLP ; RAPD ; Genetic variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Genetic variability among 49 accessions of Triticum urartu was estimated by RFLP and RAPD marker analyses, and the two data sets were compared. One T. timopheevii accession and two accessions of T. durum and T. aestivum, respectively, were included to identify T. urartu accessions closely related to these polyploid wheats. Twenty eight RFLP clones and 29 RAPD primers generated 451 and 155 polymorphic bands, respectively. The three accessions from Armenia clustered together and were well separated from all other accessions, which showed less pronounced geographical patterns. Genetic similarity and co-phenetic values calculated with RAPD markers were very similar to those calculated with RFLP markers for the intraspecific comparisons, but not for the interspecific comparisons. The identification of individual T. urartu accessions which are more related to polyploid wheats than others was not possible.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-0832
    Keywords: Prothoteca zopfii ; mastitis ; algae ; bovine ; Brazil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The isolation of Prothoteca zopfii, an algae lacking chlorophyll, from bovine mastitic milk, is described herein. The isolation was performed on 8% sheep blood agar, following incubation at 37 °C for 48 h. Based on biochemical tests, susceptibility to clotrimazole, and light and electron microscopic observation of cellular morphology the algae was identified as P. zopfii . The affected animal did not improve following treatment and had to be eliminated.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 279 (1995), S. 517-527 
    ISSN: 1432-0878
    Keywords: Avian brain ; Preoptic nucleus ; Sexual behaviour ; Ultrastructure ; Sexual dimorphism ; coturnix japonica (Aves, Phasianiformes)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The medial preoptic nucleus is a sexually dimorphic structure whose cytoarchitecture, afferent and efferent connections, and functions have been previously described. No detailed ultrastructural study has, however, been perfomed to date. Here we describe the ultrastructural organization of this important preoptic structure of the male quail. Neuronal cell bodies of the medial preoptic nucleus generally show extensive development of protein-synthesis-related organelles (rough endoplasmic reticulum, polysomes), and of secretory structures (Golgi complexes, secretory vesicles, dense bodies). Previous morphometrical studies at the light-microscopical level have demonstrated the presence of a medial and a lateral neuronal population distinguished by the size of their cell bodies (the medial neurons are smaller than the lateral neurons). The present ultrastructural investigation confirms the difference in size, but no difference has been observed in the ultrastructural organization of the neurons. In both the medial and the lateral part, the nucleus is characterized by a large variety of cell bodies, including some that, on the basis of their ultrastructure, can be considered as putative peptidergic neurons. Close contacts are frequently observed between adjacent cell bodies that are normally arranged in clusters. Various types of synaptic endings are also present, suggesting a rich supply of nerve fibers. A few glial cells are scattered within the nucleus. In view of the crucial role of this region in regulating quail sexual behavior, the large heterogeneity of neurons and of afferent nervous fibers suggest that this region might have an important role in the integration of information arriving from different brain regions.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta mathematica hungarica 23 (1972), S. 45-50 
    ISSN: 1588-2632
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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