Photosynthesis and Degree of Polymerization of Fructan during Reproductive Growth of Meadow Fescue at two Temperatures and two Photon Flux Densities

Accumulation of dry weight was measured in plant parts of meadowfescue (Festuca pratensis Huds.) that was grown at 16/11 °Cor 26/21 °C and with 20 or 60 nE cm^–2 s^–1 photosyntheticallyactive radiation. Plants reached anthesis about 3 weeks laterat 16/11 °C than at 26/21 °C and had then a higher proportionof dry weight in inflorescences and less in leaf blades. Growthtemperature had little effect on CO₂ exchange rate (CER) butplants grown at 60 nE cm^–2 s^–1 had higher CER thanthose grown at 20 nE cm^–2 s^–1. The concentration of water-soluble carbohydrates (WSC) at similargrowth stages was usually higher at 16/11°C than at 26/21°C.High radiation also led to higher WSC in stem and leaf tissue.Root tissue changed least and WSC did not exceed 10% of dryweight during the experiment. In all tissues, when WSC was high,the fructans were distributed into a group with a high degreeof polymerization (DP) and another with a low DP. The low DPgroup included sucrose, reducing sugars and fructans up to about20 units long. An apparent threshold concentration of WSC wasnecessary for synthesis of the high DP fructans. This concentrationwas near 12% for leaf tissue, about 6% for stem base tissue,and 2.5% for root tissue. The average apparent DP of the highDP fructan group was 43 to 50 for leaf tissue, 31 to 93 forstem base tissue, and 27 to 31 for roots. These characteristicsappeared to be mostly tissue dependent with less effect fromtemperature and radiation. Key words: Fructans, Meadow fescue, Environmental effects, Dry weight distribution     

Binding of netropsin to DNA and synthetic polynucleotides

The interaction of netropsin with DNA and synthetic polydeoxyribonucleotides was studied by absorption spectrophotometry and circular dichroism. The results are consistent with a model in which a netropsin molecule occupies five base pairs in binding and carries three reaction sites each capable of interacting with one AT base pair. We associate these reaction sites with the antibiotic peptide groups which probably interact with AT base pairs by a hydrogen bonding mechanism.     

Fuchsin staining with naoh clearing for lignified elements of whole plants or plants organs

Three methods that are adapted to the various consistencies of plants are as follows: 1. Samples are placed for 10-14 hr at 60° C in a 1% aqueous solution of basic fuchsin, to which 10 gm of solid NaOH per 100 ml are added. 2. Samples when taken out of 95% alcohol are placed in a 1% solution of basic fuchsin in 95% alcohol for 24 hr; after washing in water, they are placed in a 15% solution of NaOH at 60° C until cleared. 3. Samples are placed in a 15% aqueous solution of NaOH at 60° C until cleared, then for 24 hr at 60° C in 15% NaOH containing basic fuchsin. After being stained and cleared by one of these three methods, the samples are rinsed in water, dehydrated and then passed into a mixture of absolute alcohol and concentrated HC1 (3:1) for 1-15 min, rinsed in absolute alcohol, cleared in xylene and mounted in Canada balsam. The lignified tissues appear red; the others, transparent.     

A note on the performance of Rappaport's medium, compared with Rappaport-Vassiliadis broth, in the isolation of salmonellas from meat products, after pre-enrichment

Salmonellas were isolated from meat products using a slightly modified Rappaport's enrichment medium (R25), Rappaport-Vassiliadis procedure (Rappaport's broth containing 10 ml instead of 30 ml of Malachite Green solution and incubated at 43^oC instead of 37^oC), and Muller-Kauffmann's tetrathionate broth. From 255 samples, 89 were found positive with the Rappaport-Vassiliadis procedure, 83 with the R25 broth, whereas only 43 were positive with Muller-Kauffmann broth. It is concluded that the R25 medium may be used as an alternative to the more effective Rappaport-Vassiliadis broth when the only available incubation temperature is 37^oC.     

Molecular resolution of marine turtle stock composition in fishery bycatch: a case study in the Mediterranean

Based on an extensive sampling regime from both nesting populations and bycatch, frequency analyses of mitochondrial (mt) DNA control region haplotypes in the Mediterranean were used to assess the genetic structure and stock composition of the loggerhead sea turtle, Caretta caretta, in different marine fisheries. The analyses show the following. (i) In drifting longline fisheries working in Mediterranean pelagic habitats 53–55% of turtles caught originated from the Mediterranean stock; (ii) In bottom-trawl fisheries all turtle bycatch is derived from this regional stock; (iii) This regional stock contribution to fishery bycatch suggests that the population size of the Mediterranean loggerhead nesting population is significantly larger than previously thought. This is consistent with a recent holistic estimate based on the discovery of a large rookery in Libya. (iv) Present impact of fishery-related mortality on the Mediterranean nesting population is probably incompatible with its long-term conservation. Sea turtle conservation regulations are urgently needed for the Mediterranean fisheries. (v) The significant divergence of mtDNA haplotype frequencies of the Turkish loggerhead colonies define this nesting population as a particularly important management unit. Large immature and adult stages from this management unit seem to be harvested predominantly by Egyptian fisheries. (vi) Combined with other data, our findings suggest that all the nesting populations in the Mediterranean should be considered as management units sharing immature pelagic habitats throughout the Mediterranean (and possibly the eastern Atlantic), with distinct and more localized benthic feeding habitats in the eastern basin used by large immatures and adults. (vii) Between the strict oceanic pelagic and the benthic stages, immature turtles appear to live through an intermediate neritic stage, in which they switch between pelagic and benthic foods.     

In situ responses to elevated CO2 in tropical forest understorey plants

1. Plants growing in deep shade and high temperature, such as in the understorey of humid tropical forests, have been predicted to be particularly sensitive to rising atmospheric CO₂. We tested this hypothesis in five species whose microhabitat quantum flux density (QFD) was documented as a covariable. After 7 (tree seedlings of Tachigalia versicolor and Beilschmiedia pendula ) and 18 months (shrubs Piper cordulatum and Psychotria limonensis, and grass Pharus latifolius ) of elevated CO₂ treatment ( c. 700 μl litre^–1) under mean QFD of less than 11 μmol m^–2 s^–1, all species produced more biomass (25–76%) under elevated CO₂.
2. Total plant biomass tended to increase with microhabitat QFD (daytime means varying from 5 to 11μmol m^–2 s^–1) but the relative stimulation by elevated CO₂ was higher at low QFD except in Pharus .
3. Non-structural carbohydrate concentrations in leaves increased significantly in Pharus (+ 27%) and Tachigalia (+ 40%).
4. The data support the hypothesis that tropical plants growing near the photosynthetic light compensation point are responsive to elevated CO₂. An improved plant carbon balance in deep shade is likely to influence understorey plant recruitment and competition as atmospheric CO₂ continues to rise.     

人肾上腺内肽能神经的超微结构

应用抗生蛋白链菌素一生物素一过氧化物酶复合物的免疫电镜技术,在相邻切片中,分别观察人肾上腺内ＮＰＹ、ＶＩＰ、ＳＰ和ＣＧＲＰ免疫反应神经纤维的超微结构和免疫反应物的定位。ＮＰＹ和ＶＩＰ免疫反应物位于小颗粒羹泡和线粒体外膜,部分嗜铬细胞呈ＮＰＹ免疫反应阳性。ＳＰ和ＣＧＲＰ免疫反应物主要定位于大颗粒囊泡内。ＳＰ和ＣＧＲＰ免疫反应轴突与嗜铬细胞形成对称性或非对称性的轴体突轴。测量了这４种肽能神经末梢的直径,从而推测其来源,并讨论了该４种神经肽对人肾上腺的作用。     

Restriction-map variation at the zeste-tko region in natural populations of Drosophila melanogaster

Restriction-map variation in 64 X chromosome lines extracted from three different natural populations of Drosophila melanogaster was investigated with seven six-nucleotide-recognizing enzymes for a 20-kb region including the zeste and tko genes. Ten restriction-site and four length polymorphisms (two insertions and two deletions) were detected. Contrary to the predicted lower level of variation for genes on the X chromosome, the level of variation attributable to nucleotide substitution (estimated heterozygosity/nucleotide = 0.004) was similar to that previously reported for autosomal loci. The amount of insertion/deletion variation in the studied region was within the range observed in autosomal regions and thus not explainable by a simple selection model against the effects of insertional mutations. A general lack of linkage disequilibrium between polymorphic sites was observed.      

A quantitative method for assessing stages of the rat estrous cycle

The impact of gender and/or hormone variations on a wide variety of neural functions makes the choice between studying males or females (or both) of a given species difficult. Although female rats are widely used experimentally, few studies control for the stage of estrus. More detailed information about how to distinguish the various stages of the estrous cycle is needed. For the present study, vaginal smears were obtained once a day and stained using an adaptation of the Papanicolaou (PAP) procedure. Images are provided of unstained “wet” samples and the corresponding PAP stained smears illustrating the cellular profile for each stage of the cycle as well as post-ovariectomy. The different cell populations across the cycle were quantified and ratios determined to show trends between the predominant and other cell types in each stage of the estrous cycle. Both stained and unstained images and cell quantification data provide valuable guidelines for distinguishing the stages of the estrous cycle.