Relationship between postabsorptive respiratory exchange ratio and plasma free fatty acid concentrations

The relationship between overnight postabsorptive (fasting) respiratory exchange ratio (RER) and plasma FFA concentrations was addressed using data from three separate protocols, each of which involved careful control of the antecedent diet. Protocol 1 examined the relationship between fasting RER and the previous daytime RER. In Protocol 2 fasting, RER and plasma palmitate concentrations were measured in 29 women and 31 men (body mass index <30 kg·m⁻²). Protocol 3 analyzed data from Nielsen et al. (Nielsen, S., Z. K. Guo, J. B. Albu, S. Klein, P. C. O''Brien, M. D. Jensen. 2003. Energy expenditure, sex and endogenous fuel availability in humans. J. Clin. Invest. 111: 981-988.) to understand how fasting RER and palmitate concentrations relate within individuals during four consecutive measurements. The results were as follows: 1) Fasting RER was correlated (r = 0.74, P < 0.001) with the previous day''s average RER, and less so with RER variability. 2) Fasting RER was correlated (r = −0.39, P = 0.007) with fasting plasma palmitate concentrations. 3) The pattern of the RER/palmitate relationship was similar within individuals and between individuals; a negative slope was observed significantly more often than a positive slope (χ² test; P < 0.001). Our findings suggest that, despite a fixed food quotient, the slight departures from energy equilibrium in a controlled General Clinical Research Center environment can effect plasma FFA concentrations. We suggest that including indirect calorimetry as part of FFA metabolism studies may aid in data interpretation.     

Morphological gradients in the starling basilar papilla

The starling cochlea was studied with TEM at four locations along the basilar papilla to investigate gradients in morphological features over the papilla's length and width. Hair cell shape changes continuously from neural to abneural and from basal to apical. Unlike the situation in mammals, there are no distinct populations of hair cells; the previously described types (tall hair cells and short hair cells) are merely extremes in a continuum. Contacts between THC are a normal feature. Except at the base of the papilla, SHC have very large cuticular plates, suggesting a micromechanical function for these cells. In contrast to the THC, the SHC normally completely lack afferent innervation; this indicates that their function is restricted to within the basilar papilla itself. © 1992 Wiley-Liss, Inc.     

Life-history analysis of an Artemia population in a changing environment

The Anemia monica Verrill population in Mono Lake, Californiahas two generations per year. Despite similarities in the year-to-yearlife history patterns, some important differences developedbetween 1979 and 1981. The first generation hatches from overwinteringcysts in early spring and reaches maturity by the end of May.The first-generation females reproduce ovoviviparously, givingrise to a second generation which matures between mid-July andAugust. In July, both first and second generation females beginproducing overwintering cysts. The population reaches it maximumin late summer, then declines to low numbers by November. Theabundance of the first generation in June declined from a meanof 20 000 m^–2 to 2400 m^–2. Despite the smaller firstgeneration, the second generation in 1980 and 1981 was at leastas abundant as in 1979. These differences are indicative ofa change in the Artemia population dynamics in Mono Lake. ¹Address for correspondence: Hawaii Institute of Marine Biology,University of Hawaii, P.O. Box 1346 Kaneohe, HI 96744-1346,USA.     

Tauchbeobachtungen an Plankton und an Echostreuschichten

Zusammenfassung 1. Das Tauchen als Methode zur Untersuchung von Plankton und Echostreuschichten wird durch vier Beispiele erläutert: (a) Visuelle Beobachtungen an Wasserschichtungen und Grenzschichten durch Schwimmtaucher. (b) Untersuchung von Echostreuschichten durch Freitaucher, wobei sich ergab, daß angesammeltes biogenes Material in den untersuchten Sprung- beziehungsweise Streuschichten die Schallreflektion nicht beeinflußt. (c) Beobachtung von Großplankton und Feststellung von Planktonund Sestonkonzentrationen beim Tauchen mit dem Bathyscaph. (d) Untersuchung der Tiefenstreuschicht (deep scattering layer) durch Beobachtung der Vertikalwanderung bestimmter Arten des Großplanktons mit den Tauchbooten Bathyscaph und Soucoupe Plongeante. Physonectide Siphonophoren und Myctophiden standen in deutlicher Beziehung zur Tiefenstreuschicht und wurden als Echogeber erkannt.2. Die Möglichkeiten, von Tauchbooten aus quantitative und qualitative Proben von Plankton und auch vom Benthos zu nehmen, sind zur Zeit noch unzureichend. Die Entwicklung entsprechender Geräte für den wahlweisen und mehrfachen Einsatz bei demselben Tauchgang wird empfohlen.

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Diving observations on plankton and on scattering layers

Diving techniques are employed as a research tool in plankton investigations carried out in shallow water of the western Baltic Sea. Observations and samplings were made by skin divers on scattering layers corresponding to the discontinuity layers. Biogene materials, sometimes concentrated at the thermocline, are not responsible for this special kind of scattering, but rather discontinuity of salinity and temperature (Lenz 1965). For observations in deep water the use of undersea vehicles is recommended. From the Bathyscaph and the diving saucer, single plankton organisms and plankton concentrations were observed (e. g.Bernard 1958); investigations on the deep scattering layer have shown physonectid siphonophores and myctophids to be scatterers (Barham 1966). The equipment for sampling plankton and benthos from undersea vehicles is poorly developed. We need urgently gear for quantitative and qualitative sampling and for manifold use during single dives, i. e., multiple sampling gear and magazins for storage of samples.

     

Detection of point mutations in human DNA by analysis of RNA conformation polymorphism(s).

RNA molecules were found to separate into numerous metastable conformational forms upon non-denaturing gel electrophoresis. The equilibration of the conformations was accelerated by heating or mild denaturing conditions. Single-base substitutions in the sequence of the RNAs caused changes in the conformational patterns, including mobility shifts of major and minor conformations, appearance of new conformations and loss of other conformations. This sequence-dependent RNA conformational polymorphism was used to detect point mutations in p53 and, dihydrofolate reductase genes. Sense and anti-sense RNA strands corresponding to the same segment of the p53 gene gave entirely different conformational patterns. To generate the RNA, short regions of the target genes (up to about 250 bp) were amplified by the polymerase chain reaction and the resulting DNA segments transcribed to RNA by T7 RNA polymerase. The method is rapid, simple, amenable to non-radioactive visualization and was successful in several cases when DNA single-strand conformational polymorphism analysis (Orita et al. (1989) Genomics 5, 874-879) failed to detect the point mutation.     

Theoretical Basis of Protocols for Seed Storage III. Optimum Moisture Contents for Pea Seeds Stored at Different Temperatures

In previous work, we demonstrated that there was an optimummoisture level for seed storage at a given temperature (Vertucciand Roos, 1990), and suggested, using thermodynamic considerations,that the optimum moisture content increased as the storage temperaturedecreased (Vertucci and Roos, 1993b). In this paper, we presentdata from a two year study of aging rates in pea (Pisum sativum)seeds supporting the hypothesis that the optimum moisture contentfor storage varies with temperature. Seed viability and vigourwere monitored during storage under dark or lighted conditionsat relative humidities between 1 and 90%, and temperatures between-5 and 65°C. The optimum moisture content varied from 0·015g H₂O g^-1 d.wt at 65°C to 0·101 g H₂O g^-1 d.wt at15°C under dark conditions and from 0·057 at 35°Cto 0·092 g H₂O g^-1 d.wt at -5°C under lighted conditions.Our results suggest that optimum moisture contents cannot beconsidered independently of temperature. This conclusion hasimportant implications for 'ultra-dry' and cryopreservationtechnologies.Copyright 1994, 1999 Academic Press Seed storage, seed aging, seed longevity, water content, temperature, glass, desiccation damage, ultradry, Pisum sativum L., pea, cryopreservation     

Gravitropically-stimulated seedlings show autotropism in weightlessness

In a spaceflight experiment, autotropism by oat ( Avena sativa L.) coleoptiles following gravitropic responses was prominent in weightlessness: counter-reactions led to the straightening of the curved coleoptiles. This was not the case during clinorotation on earth. The autotropic reactions appeared to be related to the stimulus received during the stimulus period, i.e. the greater the response the greater the autotropic counter-reaction. Previous models of the gravitropic system which predicted that coleoptiles would not straighten in weightlessness are disproved. A modification to one of the models is proposed which includes the autotropic response observed in spaceflight. The nature of the counter-reactions in the absence of gravitropic stimulation is discussed.     

Chromatographic resolution of some cyclic sulfoximides derived from prochiral and chiral sulfoxides

Three endocyclic sulfoximides of the 1-aryl- and 1-alkyl-3-oxo-benzo[d]-isothia (IV)-azole 1-oxide type (1-substituent = 2′-carboxyphenyl, 2′-carbethoxyphenyl, and octyl, respectively) were found to be well resolved on a chiral phase derived from bovine serum albumin (BSA). Selectivities (α) of 1.74, 1.12, and 1.44, respectively, were obtained. The retention behaviour of 1-octyl-3-oxo-benzo[d]isothia(IV)-azole 1-oxide was further investigated in some detail as a function of the mobile phase composition and the elution order was established from optically active material obtained from the enantiopure sulfoxide precursor. An enantiomeric excess of 85.4% was obtained in the cyclocondensation reaction of the octyl-substituted sulfoxide precursor with hydrazoic acid to the corresponding endocyclic sulfoximide. © 1995 Wiley-Liss, Inc.