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  • 1
    ISSN: 1432-0983
    Keywords: Key words  Yarrowia lipolytica ; 3-Phosphoglycerate kinase ; Expression ; Disruption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   We have isolated the 3-phosphoglycerate kinase (PGK) gene of the yeast Yarrowia lipolytica by probing a genomic library with a PCR fragment amplified with primers deduced from two highly conserved regions of various PGKs. It is a unique sequence encoding a polypeptide of 417 residues with extensive homology to other PGKs, especially to that of Aspergillus nidulans (76% identity). The expression of the Y. lipolytica PGK1 gene proved to be higher on gluconeogenic substrates than on glycolytic ones. Haploid strains harboring a disrupted allele were able to grow on mixtures of a gluconeogenic carbon source and of a glycolytic one, but required proline supplementation in the presence of glucose, and were inhibited by glycerol.
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  • 2
    ISSN: 1432-0983
    Keywords: Yarrowia lipolytica ; 3-Phosphoglycerate kinase ; Expression ; Disruption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated the 3-phosphoglycerate kinase (PGK) gene of the yeastYarrowia lipolytica by probing a genomic library with a PCR fragment amplified with primers deduced from two highly conserved regions of various PGKs. It is a unique sequence encoding a polypeptide of 417 residues with extensive homology to other PGKs, especially to that ofAspergillus nidulans (76% identity). The expression of theY. lipolytica PGK1 gene proved to be higher on gluconeogenic substrates than on glycolytic ones. Haploid strains harboring a disrupted allele were able to grow on mixtures of a gluconeogenic carbon source and of a glycolytic one, but required proline supplementation in the presence of glucose, and were inhibited by glycerol.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 124 (1995), S. 209-213 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Penaeus semisulcatus de Haan adult gravid females, eggs and non-feeding early larvae, including Protozoea I, were used to test the hypothesis that retinoid (Vitamin A) is not required in early decapod crustacean development. In the adult gravid females, retinoids were detected only in the eyes (1.56±0.23 μg g-1 wet mass), whereas there were up to 97 μg g-1 wet mass total carotenoid in digestive gland and epidermis. This was mostly esterified, except in the ovaries, where free astaxanthin predominated (30 μg g-1). No retinoids could be detected in the eggs, the naupliar stages or Protozoea I, but free astaxanthin was metabolised exponentially, falling from 19 μg g-1 in the eggs to 4 μg g-1 in Protozoea I. This suggests that retinoid is not essential in early development and that carotenoid could be taking its place. Also, including retinoids in artificial diets appears to be unnecessary, provided adequate carotenoid is supplied.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 123 (1995), S. 435-441 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Female Penaeus esculentus Haswell were collected by 15 to 20 min duration trawls during 1990. Carotenoids were analysed in the digestive gland, abdominal muscle, the remainder of the body (hereafter called “integument”) and ovary of prawns in Stage 2 through Stage 4 (fully mature) of maturation. The only oxycarotenoids (xanthophylls) identified were astaxanthins or astaxanthin esters; occasionally low levels of β-carotene were detected in the digestive gland. The concentrations of astaxanthin monoesters (AM) and diesters (AD) were highest, with only minor amounts of free astaxanthins (Ast), except in the maturing ovaries, where free astaxanthins predominated (up to 80% of the total carotenoid). Of the total carotenoid, 82 to 94% was in the integument, but at maturity the digestive gland contained 10.7±3.4% and the ovary 5.6±0.9% of the total carotenoid. Only the ovary increased in mass during maturation, reaching up to 5.2% of total prawn mass. During this period, digestive gland concentrations of AM, AD and Ast all increased (tota 20 to 120 μg g-1); levels in the muscle and integument varied little throughout maturation (total ∼0.4 and 100 μg g-1, respectively); ovary AM levels remained low throughout (1.5 to 1.2 μg g-1), AD increased from only 2 to 5 μg g-1, but Ast increased from 2 to 34 μg g-1. Apart from the ovary, AM concentrations were the most variable. In common with other decapod Crustacea, the maturing ovary of P. esculentus contained high levels of carotenoids, indicating that these may have an important role in early development. The natural diet of P. esculentus includes a variety of carotenoids, but except for a little β-carotene, the digestive gland, where absorption occurs, contained astaxanthins, with only an occasional trace of β-carotene. This suggests that the conversion of dietary carotenoids to astaxanthin occurs soon after ingestion.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 42 (1955), S. 606-607 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular histology 15 (1983), S. 328-328 
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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  • 7
    ISSN: 1573-5117
    Keywords: Chironomus anthracinus ; oxygen deficiency ; anaerobic metabolism ; glycogen content ; Lake Esrom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth and glycogen content of Chironomus anthracinus in Lake Esrom, Denmark was examined during summer stratification in 1992 and 1993. Simultaneously, effects of oxygen deficiency on glycogen utilization and survival were experimentally studied. The population consisted of almost fullgrown 4th instar larvae in 1992 and 2nd and 3rd instar larvae in 1993. Growth rate and glycogen content changed as hypolimnetic oxygen deficiency increased. During a 1st phase of stratification dry weight and glycogen content increased (2nd and 3rd instars) or was almost constant (4th instar) but decreased significantly during the following 2nd phase. This change from growth to degrowth and utilization of endogenous glycogen reserves correlated with a change in the thickness of the microxic layer (〈0.2 mg O2 1−1) above the sediment surface. The layer increased from 2–3 m in phase 1 to 4–5 m in phase 2, and we suggest that this deteriorated the oxygen conditions and resulted in a change in larval energy metabolism from fully aerobic during the 1st phase to partly anaerobic in the 2nd phase. During the 2nd phase larval metabolism was estimated at less than 20% of normoxic rate. Experimental exposure of the larvae to anoxia indicated highly different survival of young larvae (2nd and 3rd instars) and older larvae (large 4th instars). The morality of young larvae was 50% after three days in anoxia at 10 °C, whereas only 25% of the older larvae had died after 3–4 weeks under similar conditions. Extending the treatment, however, resulted in increased death rate of the 4th instar larvae with only 10% surviving after seven weeks. The anaerobic metabolism of 4th instar larvae as estimated from glycogen degradation at 10 °C was 5% of normoxia in the interval from 0–5 days but 1.5% in the interval from 20–25 days. It is concluded that survival of C. anthracinus in anoxia is very limited, but traces of oxygen in the environment allowing for faint aerobic metabolism prolong the survival time of the larvae from a few days (2nd and 3rd instars) or a few weeks (4th instar) to probably 3–4 months.
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  • 8
    ISSN: 1573-5117
    Keywords: Chironomus anthracinus ; ontogenesis ; glycogen ; ecdysis ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Large fluctuations in glycogen content were found in larvae, pupae and adults of Chironomus anthracinus (Zetterstedt) from the profundal zone of Lake Esrom, Denmark. In 2nd, 3rd and 4th instar larvae the glycogen concentration (expressed as percentage of dry weight) increased during periods of aerobic conditions to a maximum of 25%, but decreased in periods of hypoxia longer than two months to 10–12% in young larvae. A further decrease to about 5% took place, when moulting from 2nd to 3rd or from 3rd to 4th instar occurred after overturn. Prior to pupation the glycogen concentration was restored to 26–28%. The glycogen concentration approximated 22% in young pupae, but decreased during the pupal stage and newly hatched adults contained 12–15%. Finally, the glycogen store of both males and females was further reduced during the swarming period. Thus, glycogen seems to be an important energy source (1) during periods with hypoxic conditions, (2) during periods with high internal energy requirement such as ecdyses and metamorphosis, and (3) during the non-feeding adult life stage.
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  • 9
    ISSN: 1573-5117
    Keywords: life cycles ; flight-periods ; growth ; production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The life cycle and production of Tinodes waeneri (L.) was examined at five shallow littoral localities in Lake Esrom, Denmark, during 1979/80. Five larval instars were demonstrated. The differences in temporal composition of instars indicated three different life cycles. A bivoltine strategy was shown for the most exposed locality which also had the highest average abundance equal to 11 500 ind. m−2. A univoltine population was found in the more sheltered NW part of the lake with an average density of 1 500 ind. m−2. At the three remaining stations the life cycles were partly bivoltine with wintering populations of mixed cohorts and densities between 10 500 and 3 000 ind. m−3. Two distinct flight periods with maxima in June and August were demonstrated for bi- and partly bivoltine populations. Differences in rates of growth and elimination added to the variability in life cycle. Growth rates peaked in August (5.0–7.4% d−1) at an average temperature of 20°C. Estimates of production ranged from 1.9 to 17.5 g AFDW m−2 a−1 with an average of 8.0 g AFDW m−2. The P/B ratios, which were within the expected range for uni- and bivoltine populations of trichopterans, were 5.73 for the bivoltine population and 3.31 for the univoltine population. Estimates of consumption revealed that the populations could be sustained by autochthonous epilithic production in the habitats. Variability in the quality and seasonal availability of food were judged to influence the type of life cycle.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    International journal of theoretical physics 35 (1996), S. 2597-2601 
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study the divergent behavior ofW gravity theories. As a tool, we use the Grothendieck-Riemann-Roch theorem on the compactified moduli space. We show thatW n gravity has severe divergences caused by negative masses. However, for superextension ofW n gravity the divergences by negative masses are miraculously cured by the counterpart contribution of superpartners.
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