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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 15 (1980), S. 161-168 
    ISSN: 1432-1432
    Keywords: Prebiotic synthesis ; Proteinoid ; Lysine-Rich ; ATP ; Pyrophosphate ; Peptides ; Cellular synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Lysine-rich proteinoids in aqueous solution catalyze the formation of peptides from free amino acids and ATP. This catalytic activity is not found in acidic proteinoids, even though the latter contain some basic amino acid. The pH optimum for the synthesis is about 11, but is appreciable below 8 and above 13. Temperature data indicate an optimum at 20°C or above, with little increase in rate to 60°C. Pyrophosphate can be used instead of ATP, with lesser yields resulting. The ATP-aided syntheses of peptides in aqueous solution occur with several types of proteinous amino acid.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 15 (1980), S. 359-359 
    ISSN: 1432-1432
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 15 (1980), S. 363-363 
    ISSN: 1432-1432
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1939
    Keywords: Key words Tail autotomy ; Survival ; Growth ; Reproduction ; Trivers-Willard effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Tail autotomy is a defense against predators used by many lizard species but is associated with various costs, most of which have been measured only in the laboratory. We conducted a field experiment in which we induced tail autotomy to approximately half (58%) of a marked sample (n=326) of Uta stansburiana from western Texas in the fall, and left the other half with intact tails. The following spring we determined survival, measured growth, and brought females to the laboratory to allow them to oviposit their eggs, which we incubated until hatching. Based on past studies, we anticipated inferior survival, growth, and reproduction following tail autotomy. We also predicted that females with tail loss would be energetically compromised and would alter the sex ratio of their offspring toward more daughters (as predicted by the Trivers-Willard hypothesis). Tailless lizards experienced significantly reduced survivorship, but those that survived grew the same as their tailed counterparts. Tailed and tailless females produced clutches equivalent in number of eggs and total mass. Whereas tailed females showed a significant positive relationship between average egg mass and snout-vent length, tailless females did not. Contrary to our expectations, tailless females produced heavier hatchlings than tailed ones, and sex ratios of hatchlings were equivalent for tailed and tailless females. In this population, tail loss in subadults leads to an increased risk of death, but apparently does not impose an energetic handicap such that later growth and reproduction suffer. We suggest that because tailless females are faced with decreased reproductive value, they respond by growing as much and laying as many eggs of the same mass as tailed females, despite the fact that they are also regenerating the tail. In addition, they somehow produce larger hatchlings than tailed females. Nevertheless, tailless females probably end up with lower overall lifetime fitness than tailed females, and tail loss thus induces the conditional reproductive strategy ”make the best of a bad situation”. Because tailless females produce larger, not smaller, hatchlings, they do not produce more daughters as predicted; i.e., we found no evidence for the Trivers-Willard effect following tail autotomy.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 8 (1976), S. 301-304 
    ISSN: 1432-1432
    Keywords: Proteinoids ; Protein ; Polyamino Acids ; Thermal ; Linkages ; Cell-Like
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The above authors claim to have examined critically the thermal polycondensation of amino acids −as a possible prebiotic path of chemical evolution of life−. Some of the flaws in their premises and interpretations are discussed here.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 57 (1970), S. 67-68 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Female F344/NCr rats were exposed continuously to Aroclor® 1254 (1, 3.3, 10, 33, or 100 ppm in the diet) for 7, 28, or 84 days in order to assess the accumulation of polychlorinated biphenyls (PCBs) in liver, blood, and adipose tissue. The persistence of the individual PCB congeners which are detected in liver was examined in the three tissues of additional groups of rats exposed for 7 days followed by 21 days on control diet, or for 28 days followed by 56 days on control diet. Limited accumulation of PCB congeners with low chlorine substitution (tri- and tetrachlorobiphenyls) in the liver and blood, and preferential retention of highly substituted PCB congeners (penta-and hexachlorobiphenyls) were observed in rats continuously exposed to Aroclor. In these rats, time- and dose-dependent increases in the relative levels of two congeners which cause profound phenobarbital-type induction [2,2′,3,4,4′,5′-hexachlorobiphenyl (BZ# 138) and 2,2′,4,4′,5,5′-hexachlorobiphenyl (BZ# 153)] were detected in the liver and adipose tissue. Rats receiving control diet following Aroclor treatment displayed a time- and dose-dependent decrease in the relative levels in blood, adipose and hepatic tissue of 2,3,3′4,4′-pentachlorobiphenyl (BZ# 105) and 2,3′,4,4′,5-pentachlorobiphenyl (BZ# 118), two of the major congeners showing both TCDD- and phenobarbital-type induction. These rats also displayed increases in the relative adipose levels of another relatively potent mixed-type inducer, 2,3,3′,4,4′,5-hexachlorobiphenyl (BZ# 156), and increases in adipose and hepatic levels of the pure phenobarbital-type inducer, 2,2′,4,4′,5-pentachlorobiphenyl (BZ# 99).
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  • 8
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) levels were measured by capillary gas chromatography with electron capture detection in liver and blood serum of male F344/NCr rats exposed for 2 weeks to DDD at dietary concentrations ranging from 8.51 ppm to 2,000 ppm. DDD burdens in serum ranged from 〈0.006 μM (limit of detection) in control rats to 1.1 μM in the rats fed DDD at 2,000 ppm. The corresponding liver burdens in these animals ranged from 〈0.006 μmol/kg liver (controls) to 11 μmol/kg liver in rats fed DDD at 2,000 ppm. Levels of DDE in serum or liver were undetectable (〈0.006 μM in serum; 〈0.006 μmol/kg liver) in rats fed control diet or diet containing 8.51 or 25.5 ppm DDD. The liver and serum burdens of DDE increased with dietary DDD concentration, reaching a maximum of 0.53 μM in serum and 4.7 μmol/kg liver in rats fed 2,000 ppm DDD. As a percentage of total DDD equivalents detected in liver or serum, the DDE burdens increased to a maximum of 36% and 31% in the serum and liver, respectively, of rats fed 689 ppm DDD. The possibility that the DDE might have been generated artifactually in the diet prior to administration to the rats was ruled out by analysis with capillary gas chromatography of the diet containing 2,000 ppm DDD. The identification of DDE as a metabolite in liver extracts of rats fed 2,000 ppm DDD was confirmed with GC-MS. The results confirmed the presence of DDE as a metabolite of DDD.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 15 (1959), S. 81-84 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Bei Überschuss von Glutaminsäure und Asparaginsäure werden zahlreiche Aminosäuren thermisch kopolymerisiert. Das Studium der Reaktionen und Nebenreaktionen führt zu einer Theorie über den thermischen Ursprung biochemischer Systeme.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 29 (1973), S. 962-964 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Nachweis, dass die alkalische Hydrolyse des Phthalimids durch eine N-Succinimidgruppe erhöht wird. Während der alkalischen Hydrolyse des Polysuccinimids fällt die Reaktionsgeschwindigkeit infolge Auftretens negativer Ladungen ab.
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