A RESEARCH NOTE: COMPARISON OF TIME-INTENSITY AND THRESHOLD MEASURES FOR DETERMINING BITTER TASTE SENSITIVITY OF CAFFEINE USER AND NONUSER

Two taste sensitivity measures (detection threshold and time-intensity [T/I]) were applied to evaluate bitter taste sensitivity of caffeine in both caffeine nonusers (n = 12) and users (n=12, caffeine consumption level; > 300mg/day). Taste thresholds of caffeine were significantly different between nonusers and users in two test sessions (p < 0.01 in first and p < 0.05 in second). In T/I measures, only the difference in peak height was observed between the two groups in one of two test sessions. The other two measures, half width and area of T/I curves showed no significant difference.     

COMPARISON OF SIGMPLOT, PROBIT, AND EXTREME-VALUE METHODS FOR THE ANALYSIS OF THRESHOLD DATA

Two panels consisting of 12 and of 14 members, respectively,evaluated solutions of ethyl caprylate at different concentrationsto establish flavor detection thresholds. The resulting frequenciesof success at each concentration level were analyzed by a probitmethod and Drake's procedure (1975). These two methods in turnwere compared with extreme-value analysis. Agreement among thethree methods was good. The lowest threshold observed was 0.00069ppm and the highest, 26.9 ppm. An extreme-value plot is presentedfor 59 determinations obtained in prior studies and the 26 valuesof this study. The limitations and advantages of each methodof calculation are discussed as are precautions relative tothe way the extreme-value data should be accumulated or arrayedfor analysis. ^*Station Statistician, Georgia Agricultural Experiment Station.     

A SENSITIVE ENZYMATIC-ISOTOPIC METHOD FOR THE ANALYSIS OF TYRAMINE IN BRAIN AND OTHER TISSUES

Abstract— An enzymatic-isotopic assay for the measurement of tyramine with a sensitivity of 1.0 ng has been developed. Using this assay, the endogenous content of tyramine in various tissues from adult rats has been determined. The highest tyramine content was found in rat heart atria, followed by salivary gland, kidney, and brain. Within the brain the distribution of tyramine is heterogeneous and the highest tyramine content was localized in the striatum.     

β-CARBOLINES: A TOOL FOR INVESTIGATING STRUCTURE-ACTIVITY RELATIONSHIPS OF THE HIGH-AFFINITY UPTAKE OF SEROTONIN,NORADRENALINE, DOPAMINE,GABA AND CHOLINE INTO A SYNAPTOSOME-RICH FRACTION OF VARIOUS REGIONS FROM RAT BRAIN1

Abstract— Tetrahydronorharmane (tryptoline), the condensation product of tryptamine and formaldehyde, inhibits the high-affinity uptake of serotonin and to a smaller extent that of noradrenaline into a synaptosome-rich fraction from the hippocampus and hypothalamus respectively of rats. The uptake mechanisms of dopaminergic neurones of the hypothalamus, cholinergic neurones of the hippocampus, and GABA-ergic neurones of the cerebral cortex are affected to a much lesser degree. Substitution of tetrahydronorharmane by fluor-, chlor-, methyl-, hydroxy-, methoxy-, and catechol-groups alters the inhibition. Drugs with substituents which attract electrons are relatively good inhibitors of the uptake of serotonin. The indole-ring contributes to the binding of the molecule probably by forming a charge transfer complex with the uptake molecule. Pyrido (3,4-b)-indoles (harmala alkaloids) are weak inhibitors of the serotonin-uptake compared with respective piperidoindoles (tetrahydro-β-carbolines). The potency of the drugs to inhibit uptake is different for each uptake system. The order among the drugs with respect to their affinity for the uptake site varies, too.     

阿胶冲剂与阿胶的化学成分对比分析研究

阿胶在我国有着悠久的历史,是常用滋补中药,具有许多特殊的功效,国内外享有盛誉。据《本草纲目》及《本草纲目拾遗》等介绍,阿胶在明代以前系用(沙牛)牛,水牛,驴皮或猪、马、驼皮等杂皮熬制而成。自清代始一律采用黑驴皮熬制。以往服用阿胶必须将阿胶先用水浸泡后,然后加热溶解后才能服用.为了克服这一缺点,山东化工学院研制了一种用开水冲服的阿胶新制剂——阿胶冲剂.为了弄清阿胶经物理方法处理后的化学组成成份与原阿谱的化学组成成分的不同变化。我们对其所含微量元素、氨基酸进行了对比分析.另外,本文首次报道了阿胶及阿胶冲剂的红外光谱分析结果.     

KINETIC ANALYSIS OF PHENYLALANINE-INDUCED INHIBITION IN THE SATURABLE INFLUX OF TYROSINE, TRYPTOPHAN, LEUCINE AND HISTIDINE INTO BRAIN CORTEX SLICES FROM ADULT AND 7-DAY-OLD RATS

—An attempt was made to isolate the saturable uptake from the unidirectional influx of amino acids into tissue slices and to estimate the transport constants and maximal velocities of saturable transport. The method was applied to studies on the inhibition of phenylalanine in the saturable influx of tyrosine, tryptophan, histidine and leucine into brain cortex slices from adult and 7-day-old rats. In both age groups phenylalanine inhibited the influx of the other amino acids, and vice versa. The apparent transport constants of the other amino acids increased in the presence of phenylalanine more noticeably in the slices from 7-day-old rats than in those from adult rats, whereas the concomitant influx of phenylalanine was inhibited less in the slices from 7-day-old rats. In immature animals in vivo competition between amino acids may play a more marked role in the supply of amino acids from plasma to brain, as the transport systems in brain slices from 7-day-old rats become saturated with extracellular amino acids more readily than do the transport systems in brain slices from adult rats.     

A MODEL APPROACH FOR SIZE-SELECTIVE COMPETITION OF MARINE PHYTOPLANKTON FOR FLUCTUATING NITRATE AND AMMONIUM1

Phytoplankton size-selective competition for fluctuating nutrients was studied with the use of a numerical model, which describes nitrate and ammonium uptake, nitrate reduction to ammonium, and growth as a function of cell she under fluctuating nitrogen limitation. The only size-dependent parameter in the model was the cell nutrient quota. Related to this, the cell surface area per biomass was negatively correlated to cell volume, and the vacuole volume per biomass ratio was positively correlated to cell volume. Simulations showed an inverse correlation between the maximum specific growth rate and cell size under steady-state conditions. With nitrate as the limiting nitrogen source, nitrogen quotas were always higher than with ammonium at the same specific growth rate. Net passive transport of ammonium due to unspecific diffusion of ammonia across the plasma membrane decreased the affinity for ammonium, whereas the affinity for nitrate was not influenced. Transient state-specific ammonium uptake was not dependent on cell size. However, small algae always have the highest specific growth rate in ammonium-controlled systems according to our model. Transient state nitrate uptake rate was positively correlated to cell size because larger algae have a higher vacuole volume per biomass, in which nitrate can be stored. Despite their lower maximum growth rate, larger algae became dominant during simulations under fluctuating nitrate supply when amplitude of and the period between nitrate pulses were high enough. Results from model simulations were qualitatively validated by earlier observations that large diatoms become dominant under fluctuating conditions when nitrate is the main nitrogen source.     

A SEAWATER MEDIUM FOR DINOFLAGELLATES AND THE NUTRITION OF CACHONINA NIEI1

Two media have been devised: an enriched seawater medium for culture of dinoflagellates and a defined medium for rapid growth of the dinoflagellate Cachonina niei. A wide range in salinity (10.23–42.38 g/liter NaCl) is tolerated by C. niei. Below 0.6 g/liter MgSO₄, 0.19 g/liter KCl, and 0.22 g/liter CaCl₂, the generation time greatly increases. Increase in MgSO₄ to 7.22 g/liter, KCl to 1.12 g/liter or CaCl₂ to 2.22 g/liter has little effect on generation time. The temperature optimum is 19–23 C. Saturating light intensity for growth is 1000 ft-c and for photosynthesis (determined manometrically) is slightly less than 2000 ft-c. Cachonina niei requires B₁₂ and thiamin. Neither silicate nor its competitive inhibitor germanate affects generation time or cell yield indicating silicon is not required. Of a variety of buffers tested, Tris is the best. Optimal growth occurs at pHs of 7.5–8.3. Glycerol is inhibitory and does not support dark growth.     

MULTILEVEL ANALYSIS OF MORPHOMETRIC DATA FROM NATURAL PLANT POPULATIONS: INSIGHTS INTO ONTOGENETIC,GENETIC, AND SELECTIVE CORRELATIONS IN DALECHAMPIA SCANDENS

I examined patterns of covariation of three morphometric blossom characters [gland area (GA), gland–stigma distance (GSD), and bract length (BL)] within genets, among genets, and among populations of the tropical vine, Dalechampia scandens (Euphorbiaceae). Covariance between BL and GA was evenly distributed among the three levels. This observation, coupled with developmental information, indicates that the two characters change size similarly during development, that there is probably genetic covariance between them (apparently caused by pleiotropy), and that the genetic covariance may have constrained (at least proximally) the course of population differentiation with respect to these characters. Most covariance between GSD and GA occurred at the among-population level. This observation, coupled with developmental information, indicates that there is negligible ontogenetic covariance and that within populations there is probably little or no genetic covariance between the two characters. Among-population covariance has probably been caused by natural selection operating in a correlated fashion on characters that functionally interact in pollination.     

A METHOD FOR THE ISOLATION AND ESTIMATION OF GABA, GLUTAMATE AND GLUTAMINE FROM COMPLEX MIXTURES BY A COMBINATION OF ENZYMIC INTERCONVERSION AND FORMATION OF 1-DIMETHYLAMINONAPHTHALENE-5-SULPHONYLBUTYROLACTAM

Abstract— A method is presented which allows the isolation and estimation of GABA, glutamate and glutamine in extracts of nervous tissue. It depends on the enzymic conversion of the last two compounds to GABA, before isolating the GABA as DNS-γ-butyrolactam. The low polarity of this compound makes this possible without the use of chromatography. Furthermore, the specific radioactivities of these 3 compounds in a complex mixture may be found without elaborate separation procedures. Details are given of optimum reaction conditions, and comparisons made with other methods of estimation of these amino acids.     

籼稻稻米外观品质的细胞质,母体和胚乳遗传效应分析

利用浙协2号A等9个籼型不育系和T49等5个籼型恢复系进行不完全双列杂交,研究了籼稻稻米外观品质的遗传效应．结果表明,稻米外观品质性状的表现受制于胚乳、母体和细胞质三套遗传体系．糙米长、长宽比和长厚比等性状以母体遗传率为主,而糙米宽和糙米厚则以胚乳直接遗传率为主,糙米长和长宽比等性状的细胞质遗传率亦很重要．结果还发现外观品质性状间存在着较强的遗传相关,其中糙米长与糙米宽、糙米长与糙米厚、糙米宽与糙米厚、糙米宽与长宽比、糙米厚与长厚比以及糙米长宽比与长厚比性状间以胚乳直接加性和母体加性相关为主．而糙米长与长宽比、糙米长与长厚比、糙米宽与长厚比以及糙米厚与长宽比性状间则以胚乳直接显性和母体显性相关为主．就外观品质的总体情况而言,遗传效应预测值表明参试亲本以V20A、作5A和测早2-2较好,其各种遗传效应能够显著改善稻米品质性状。V20A／102和作5A／测早2-2等组合具有较好的稻米外观品质．