Improved allometric models to estimate the aboveground biomass of tropical trees

Terrestrial carbon stock mapping is important for the successful implementation of climate change mitigation policies. Its accuracy depends on the availability of reliable allometric models to infer oven‐dry aboveground biomass of trees from census data. The degree of uncertainty associated with previously published pantropical aboveground biomass allometries is large. We analyzed a global database of directly harvested trees at 58 sites, spanning a wide range of climatic conditions and vegetation types (4004 trees ≥ 5 cm trunk diameter). When trunk diameter, total tree height, and wood specific gravity were included in the aboveground biomass model as covariates, a single model was found to hold across tropical vegetation types, with no detectable effect of region or environmental factors. The mean percent bias and variance of this model was only slightly higher than that of locally fitted models. Wood specific gravity was an important predictor of aboveground biomass, especially when including a much broader range of vegetation types than previous studies. The generic tree diameter–height relationship depended linearly on a bioclimatic stress variable E, which compounds indices of temperature variability, precipitation variability, and drought intensity. For cases in which total tree height is unavailable for aboveground biomass estimation, a pantropical model incorporating wood density, trunk diameter, and the variable E outperformed previously published models without height. However, to minimize bias, the development of locally derived diameter–height relationships is advised whenever possible. Both new allometric models should contribute to improve the accuracy of biomass assessment protocols in tropical vegetation types, and to advancing our understanding of architectural and evolutionary constraints on woody plant development.     

New N-substituted 7-aminocephalosporanic acid derivatives as potential agents against Streptococcus pneumoniae. Synthesis and in vitro activity

The synthesis and the antimicrobial properties of a new series of cephalosporinic beta-lactam antibiotics is described. The data reported in the present paper show the potential of this type of substituted cephalosporins as new anti Gram-positive antibiotic drugs. In fact, all compounds tested showed a good in vitro antibacterial activity against the most relevant Gram-positive pathogens including resistant species that currently represent unmet medical need. On the contrary, the new synthesized compounds were found to be completely devoid of any activity on Gram-negative bacteria up to a concentration of the single agent of 128 microg/ml.     

A Structure-Guided Mutation in the Major Capsid Protein Retargets BK Polyomavirus

Viruses within a family often vary in their cellular tropism and pathogenicity. In many cases, these variations are due to viruses switching their specificity from one cell surface receptor to another. The structural requirements that underlie such receptor switching are not well understood especially for carbohydrate-binding viruses, as methods capable of structure-specificity studies are only relatively recently being developed for carbohydrates. We have characterized the receptor specificity, structure and infectivity of the human polyomavirus BKPyV, the causative agent of polyomavirus-associated nephropathy, and uncover a molecular switch for binding different carbohydrate receptors. We show that the b-series gangliosides GD3, GD2, GD1b and GT1b all can serve as receptors for BKPyV. The crystal structure of the BKPyV capsid protein VP1 in complex with GD3 reveals contacts with two sialic acid moieties in the receptor, providing a basis for the observed specificity. Comparison with the structure of simian virus 40 (SV40) VP1 bound to ganglioside GM1 identifies the amino acid at position 68 as a determinant of specificity. Mutation of this residue from lysine in BKPyV to serine in SV40 switches the receptor specificity of BKPyV from GD3 to GM1 both in vitro and in cell culture. Our findings highlight the plasticity of viral receptor binding sites and form a template to retarget viruses to different receptors and cell types.     

Monosaccharide and aminoacid composition of mucilage material produced from a mixture of four phytoplanktonic taxa

A series of multi-taxa cultures containing five blue-green algae, three diatoms, one prymnesiophyte and one dinoflagellate was set up by using as inoculum sea water collected during a mucus-forming phytoplankton bloom in Euboikos Gulf, Aegean Sea. The cultured algae produced mucilage material that undergone quantitative and qualitative pigment, monosaccharide and aminoacid analyses with the use of HPLC methodology. Eight pigments (chlorophyll α, chlorophyll c, fucoxanthin, zeaxanthin, 19′-butanoylofucoxanthin, 19′-hexanoylofucoxanthin, peridinin and phaeophytin α) were identified and confirmed the species viability and their state of senescence. The qualitative composition of the recorded 8 monosaccharides (glucose, galactose, xylose, fucose, mannose, rhamnose, arabinose and glucosamine) and 15 aminoacids (arginine, glutamine, aspartate, serine, lysine, glysine, threonine, alanine, tyrosine, methionine, valine, phenylalanine, isoleucine, leucine and histidine) was similar in all cultures, but their quantitative composition differed among them and this might be due to their differences in species composition. The results also showed that the relative abundance of aminoacids and monosaccharides depended on the physiological state of the cells, the former being more abundant during the exponential phase and the latter mainly during the stationary phase of the cultures.     

Effect of stimulus volume on taste detection threshold for NaCl

An ascending method of limits with a three stimulus forced choiceresponse procedure was used to determine detection thresholdsfor NaCl at stimulus volumes of 0.05, 0.5 and 0.9 ml, with andwithout an intertrial 0.9-ml water rinse. Results suggestedan inverse relationship between stimulus volume and taste threshold.The rinse condition produced a small non-significant improvementin detection for all volumes. Thresholds, varying from 1.8 to5.6 mM, were similar to those determined by other investigatorsin which much larger stimulus volumes were used. These resultsdemonstrate that a rapid, small volume, no-rinse method of thetype commonly used in clinical practice to measure taste detectionthresholds can be used to yield valid estimates of taste threshold.     

Changes in nucleic acids, protein and ribonuclease activity during maturation of peanut seeds

Changes in weight, protein, RNA, DNA and ribonuclease activityduring maturation of the peanut seed have been studied. Theinvestigation period began with fruits harvested four weeksafter the pegs turned at right angles in the soil and continuedthrough the fourteenth week. Fresh weights of both cotyledonsand embryonic axes increased rapidly during early maturation(8 weeks) and continued in the cotyledons through 12 weeks.The water content at maturity was still adequate for enzymaticprocesses at 45% and 39%, respectively, for embryonic axes andcotyledons. The levels of DNA and RNA also increased rapidlyduring early maturation of both cotyledons and embryonic axes.DNA content decreased during the remainder of maturation whileRNA decreased from 8 to 11 weeks in the cotyledons and thenincreased during the after-ripening period to a value near itsprevious maximum at 8 weeks. RNA levels in the embryonic axesunderwent a gradual increase throughout maturation. The largedecrease in cotyledonary RNA during weeks 8 through 11 couldbe related to increased RNase activity during the period. ¹ Paper number 3370 of the Journal Series of the North CarolinaState University Agricultural Experiment Station, Raleigh, NorthCarolina 27607, U. S. A. ² Present address: Department of Botany, Arts and Sciences,University of the Phillippines, Diliman, Q. C., Phillipines. (Received December 22, 1971; )     

In vitro saprotrophic basidiomycetes tolerance to pendimethalin

Pendimethalin is a dinitroaniline herbicide classified among the persistent-bioaccumulative toxics. In this paper, the tolerance to this herbicide has been studied in isolates of basidiomycetes (10 species including 9 wood-rotting and 1 litter fungi), collected in different areas of the Campania region (South Italy). The isolates were grown on two different agar media, rich and poor for the presence/absence of dextrose and NH₄NO₃, and amended with 0, 100 and 500 ppm herbicide. The mycelial growth was recorded daily, and statistical analysis of fungal growth rates, determined via linear regression, allowed us to compare the hyphal extension of various macrofungi in presence of herbicide. These data represent the adaptation capacity of the fungal organisms to the peculiar environmental situation. In amended agar, all fungi exhibited a certain tolerance to pendimethalin and, normally, the fungal growth decreased with the increasing of pollutant concentration. Nevertheless, in some cases, the difference of ground reflected the different agar media. In fact, the growth of Agrocybe aegerita, in rich agar decreased with the increase of herbicide dose, while in poor agar it increased with the pollutant. Among the examined fungi, A. aegerita was the species which resulted the most tolerant to herbicide, showing growth to about 70% of the control to the highest concentrations of pollutant and for the two different agar media.Scientific relevance of the paperNo published report is available regarding pendimethalin herbicide biodegradation with basidiomycetes; therefore this work represented the first and preliminary investigation as regards. It's directed to determine the fungal tolerance to the pollutant.