bluuebunny/crossref_metadata_2025 huggingface dataset:
Pseudo-oxocarbons complexes - complexation of 2,4-bis(dicyanomethylene)-cyclobutane-1,3-dione dianion with copper. X-ray identification and electrochemical properties of the dianion and copper(I) and (II) complexes
Authors: Fabre Paul-Louis , Pena Christophe , Galibert Anne Marie , Soula Brigitte , Bernardinelli Gérald , Donnadieu Bruno , Castan Paule
Published: April 2011

The compound (Ph4P)2(trans-cdcb)·2H2O (trans-cdcb2- = 2,4-bis(dicyanomethylene)-cyclobutane-1,3-dione dianion) has been synthesized and characterized by X-ray crystallography. Crystal data: triclinic, space group P1, a = 10.829(2) Å, b = 11.297(2) Å, c = 11.515(2) Å, α = 79.61(1)°, β = 68.54(1)°, γ = 63.49(1)°, V = 1172.9(4) Å3, Z = 1, R = 0.036, Rw = 0.047. With the dianion as a ligand, two complexes have been obtained and characterized by X-ray crystallography, UV-visible spectroscopy, and electrochemistry. The copper(II) complex [Cu(trans-cdcb)(H2O)4·2H2O]n consists of polymeric chains with copper atoms bonded to two of the nitrile groups of the ligand. Crystal data: monoclinic, space group P21/c, a = 9.6366(6) Å, b = 7.1292(3) Å, c = 10.7018(6) Å, β = 99.603(4)°, V = 724.92(7) Å3, Z = 2, R = 0.026, Rw = 0.041. The copper(I) complex[Cu2(trans-cdcb)(CH3CN)4·2CH3CN]n consists of polymeric chains with copper atoms bonded by all the four nitrile groups of the ligand. Crystal data: monoclinic, space group P21/n, a = 10.654(2) Å, b = 8.736(1) Å, c = 14.654(3) Å, β = 109.01(2)°, V = 1291.3(9) Å3, Z = 2, R = 0.037, Rw = 0.041. In CH3CN solution, the copper complexes are dissociated. Moreover, copper(II) is reduced into copper(I) by the dianion. Electrochemistry in the solid state (polymer coated electrode) showed the redox transitions of the different compounds.Key words: pseudo-oxocarbons, X-ray diffraction, copper(II) complex, copper(I) complex, electrochemical behaviour.
Synthesis of aspartic acid derivatives useful for the preparation of misacylated transfer RNAs
Authors: Lodder Michiel , Crasto Curtis F , Laikhter Andrei L , An Haoyun , Arslan Tuncer , Karginov Vladimir A , Short III Glenn F , Hecht Sidney M
Published: April 2011

Several derivatives of aspartic acid were protected on Nαas their NVOC derivatives, and on the side chain carboxylates as nitroveratryl esters. Following activation as the cyanomethyl esters, these fully protected aspartate derivatives were converted to the respective pdCpA esters. The protected aspartyl-pdCpA esters were then utilized as substrates for T4 RNA ligase in the presence of in vitro transcripts of tRNA lacking the pCpA dinucleotide normally found at the 3'-end. In this fashion, several misacylated tRNAs were prepared; following photolytic deprotection, these were employed successfully for incorporation into proteins at predetermined positions.Key words: aminoacylated nucleotides, amino acid protection, protein synthesis, tRNA activation.
Purification, characterization, and antifungal activity of chitinase from Fusarium chlamydosporum, a mycoparasiteto groundnut rust, Puccinia arachidis
Authors: Mathivanan N , Kabilan V , Murugesan K
Published: April 2011

Chitinase (EC 3.2.1.14) was isolated from the culture filtrate of Fusarium chlamydosporum and purified by ion-exchange chromatography and gel filtration. The molecular mass of purified chitinase was 40 kDa as estimated by sodium dodecyl sulfate  polyacrylamide gel electrophoresis. Chitinase was optimally active at a pH of 5 and stable from pH 4 to 6 and up to 40°C. Among the metals and inhibitors tested, mercuric chloride completely inhibited the enzyme activity. The activity of chitinase was high on colloidal and pure chitin. The purified chitinase inhibited the germination of uredospores of Puccinia arachidis and also lysed the walls of uredospores and germ tubes. The results from these experiments indicated that chitinase of F. chlamydosporum plays an important role in the biocontrol of groundnut rust. Key words: Fusarium chlamydosporum, chitinase, purification, Puccinia arachidis, uredospores.
Cloning of the Nocardia corallina polyhydroxyalkanoate synthase gene and production of poly-(3-hydroxybutyrate-co-3-hydroxyhexanoate) and poly-(3-hydroxyvalerate-co-3-hydroxyheptanoate)
Authors: Hall Brian , Baldwin Jennifer , Rhie Ho Gun , Dennis Douglas
Published: April 2011

The polyhydroxyalkanoate (PHA) synthase gene (phaCNc) from Nocardia corallina was identified in a lambda library on a 6-kb BamHI fragment. A 2.8-kb XhoII subfragment was found to contain the ntact PHA synthase. This 2.8-kb fragment was subjected to DNA sequencing and was found to contain the coding region for the PHA synthase and a small downstream open reading frame of unknown function. On the basis of DNA sequence, phaCNc is closest in homology to the PHA synthases (phaCPaI and phaCPaII) of Pseudomonas aeruginosa (approximately 41% identity and 55% similarity). The 2.8-kb XhoII fragment containing phaCNc was subcloned into broad host range mobilizable plasmids and transferred into Escherichia coli, Klebsiella aerogenes (both containing a plasmid bearing phaA and phaB from Ralstonia eutropha), and PHA-negative strains of R. eutropha and Pseudomonas putida. The recombinant strains were grown on various carbon sources and the resulting polymers were analyzed. In these strains, the PHA synthase from N. corallina was able to mediate the production of poly(3-hydroxybutyrate-co-3-hydroxy-hexanoate) containing high levels of 3-hydroxyhexanoate when grown on hexanoate and larger even-chain fatty acids and poly(3-hydroxyvalerate-co-3-hydroxyheptanoate) containing high levels of 3-hydroxyheptanoate when grown on heptanoate or larger odd-chain fatty acids. Key words: polyhydroxyalkanoates (PHAs), Nocardia corallina, biodegradable, polyester.
Sampling to determine nodule occupancy of soybean (Glycine max (L) Merr.) by Bradyrhizobium japonicum strains
Authors: Revellin Cécile , Denis Jean-Baptiste , Catroux Gérard
Published: April 2011

The confidence interval of the percentage of soybean (Glycine max. (L.) Merr.) nodule occupancy by two strains of Bradyrhizobium japonicum was studied using samples of nodules per plant varying by multiples of 8 (8-56). These samples were recovered from all of the nodules of four sets of 21-24 plants grown in soil colonized only by these strains and typed using strain-specific sera. Approximate confidence intervals (ACI) were estimated (from the ANOVA model) using the formula, length of ACI = 4 [(0.040/P) + (0.278/PN)]1/2, where P is the number of sampled plants and N is the number of nodules characterised for each plant. The estimated ACI decreased when the number of plants sampled increased and decreased to a lesser extent when the number of nodules typed per plant increased. It was possible to define a plant and nodule sampling strategy to minimize the labor and time required to get acceptable ACI values. Under our experimental conditions, when 192 nodules were typed, combinations of 24 plants × 8 nodules per plant and 32 plants × 6 nodules per plant were the most satisfactory, corresponding to calculated ACI of 22.3 and 20.8%, respectively.Key words: Bradyrhizobium japonicum, competition, method, nodule occupancy, soybean.
Isolation and characterization of a 9-fluorenone-degrading bacterial strain and its role in synergistic degradation of fluorene by a consortium
Authors: Casellas Mercè , Grifoll Magdalena , Sabaté Jordi , Solanas Anna Maria
Published: April 2011

Pseudomonas mendocina MC2, able to use 9-fluorenone but not fluorene as its sole source of carbon and energy, was isolated. Identification of metabolites in growth media and washed cell suspensions indicated that strain MC2 metabolizes 9-fluorenone via angular dioxygenation of the ketone, to give 1,1a-dihydroxy-1-hydro-9-fluorenone, followed by the opening of the five-membered ring and further degradation of the resulting biphenyl derivative by reactions akin to those of biphenyl metabolism, which produce phthalate as an intermediate. The aim of this research was to study the biodegradation of fluorene by a co-culture of strain MC2 and Arthrobacter sp.strain F101, which grows on fluorene and simultaneously transforms a fraction of the substrate to 9-fluorenone, which accumulates as a dead-end product. Growing with 0.1 g fluorene/L, Arthrobacter sp. strain F101 caused the total removal of this compound from the cultures, but when this strain was grown with 1g fluorene/L, only 16% of the fluorene was used. The addition of 9-fluorenone to cultures growing on fluorene showed that 9-fluorenone inhibits fluorene degradation. Finally, when Pseudomonas mendocina MC2 and Arthrobacter sp. strain F101 were co-cultured with 1g fluorene/L as a sole source of carbon and energy, the growth of the strains completely removed fluorene in 2 days. 9-Fluorenone did not accumulate and the carbon assimilation into cell biomass was estimated as approximately 46%. Key words: microbial consortium, fluorene, 9-fluorenone, biodegradation.
Effect of nutrient composition on the in vitro growth of urogenital lactobacilli and uropathogens
Authors: Reid Gregor , Soboh Foaud , Bruce Andrew W , Mittelman Marc
Published: April 2011

Previous clinical studies have shown that nutrients and probiotic agents can alter the composition of the vaginal flora. The present in vitro study has shown that uropathogens have a growth advantage over lactobacilli, but potentially there are natural substances that could be applied vaginally to stimulate lactobacilli growth to the detriment of the pathogens. When chemically defined medium representative of vaginal fluid at pH 5.5 was supplemented with skim milk, it acted as a better substrate for Lactobacillus rhamnosus GR-1 than for uropathogenic bacteria and Candida albicans. Lactobacillus MRS medium, even at pH 4.5, supports the growth of pathogens, but when supplemented with ascorbic acid or EDTA, Lactobacillus growth was significantly higher. When L. rhamnosus GR-1 was coincubated in a combined nutrient composition of vitamins and lactose, it survived better than Escherichia coli and Enterococcus faecalis. These in vitro results provide a basis for testing nutritional supplements to alter the urogenital flora in an attempt to enhance restoration and maintenance of a normal disease-free state.Key words: nutrients, lactobacilli, uropathogens, growth.
Viable but nonculturable coccoid forms of Prolinoborus fasciculus (Aquaspirillum fasciculus)
Authors: Koechlein David J , Krieg Noel R
Published: April 2011

Following active growth, the aquatic gram-negative rod Prolinoborus fasciculus (Aquaspirillum fasciculus) exhibited a mass conversion from its culturable rod form to a nonculturable coccoid form. Chloramphenicol did not prevent the conversion. Attempts to obtain variants that would not convert to the coccoid form were unsuccessful. Although the coccoid form fluoresced with acridine orange, agarose gel electrophoresis revealed extensive rRNA degradation. Poly-beta-hydroxybutyrate, abundant in the vegetative rods, was not detectable in the coccoid cells. The results suggest that the coccoid form of P. fasciculus is a degenerative form rather than part of a life cycle.Key words: Aquasprillum fasciculus, viable but nonculturable.
Tannin-tolerant ruminal bacteria from East African ruminants
Authors: Odenyo A A , Osuji P O
Published: April 2011

Three strains of tannin-tolerant rumen bacteria were isolated from enrichment cultures of rumen microflora of sheep, goat, and antelope and established in medium containing high concentrations of crude tannin extract or tannic acid. These three strains (EAT2, ES3, and EG19), characterized as Selenomonas species, were curved rods, obligately anaerobic, Gram negative, highly motile, and grew in media containing 50 g of tannin extract/L and 50-70 g of tannic acid/L. Strain EAT2 was able to hydrolyze gallic acid, while strains ES3 and EG19 hydrolyzed tannic acid but not gallic acid. All isolates were able to grow in media containing up to 8 g of condensed tannins/L. Growth was very slow when soluble carbohydrate was not added to the medium.Key words: tannin, rumen, bacteria, tannic acid, gallic acid, Selenomonas.
Three new insect-associated species of the yeast genus Candida
Authors: Kurtzman C P , Robnett C J
Published: April 2011

Three new species of Candida are described that were determined to be genetically isolated from all other currently accepted ascomycetous yeasts based on their sequence divergence in the species-variable D1/D2 domain of large subunit (26S) ribosomal DNA. One of the species was isolated from an ambrosia beetle, whereas the other two were from the frass of wood-boring beetle larvae. The new species and their type strains are the following: Candida ontarioensis NRRL YB-1246 (CBS 8502), Candida tammaniensis NRRL Y-8257 (CBS 8504), and Candida trypodendroni NRRL Y-6488 (CBS 8505).Key words: Candida, new yeast species, ribosomal DNA, molecular systematics.
Neutral lipids, phospholipids, and a betaine lipid of the snow mold fungus Microdochium nivale
Authors: Istokovics Anita , Morita Naoki , Izumi Kazuo , Hoshino Tamotsu , Yumoto Isao , Sawada Michiko Takagi , Ishizaki Kozo , Okuyama Hidetoshi
Published: April 2011

The hyphae of the snow mold Microdochium nivale contained lipids in a yield of about 10% w/w of the dry matter of hyphae. The total lipid was fractionated into neutral and polar lipid fractions. In the neutral lipid fraction, triacylglylcerol was the sole major component. As minor components, ergosterol, diacylglycerol, free fatty acid, and fatty acyl ergosterol were identified. The polar lipid fraction contained phospholipids, glycolipids, and a lipid containing neither phosphorus nor sugar. Phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol, phosphatidylserine, and phosphatidic acid were identified as phospholipids. The polar lipid fraction included at least four kinds of glycolipids that have not been identified. A very unusual lipid in fungi, a betaine lipid, diacylglyceryltrimethylhomoserine, was identified by chemical and physicochemical analyses. The level of the neutral lipid fraction, which accounted for 60% of the total lipid in hyphae at the exponential phase, was significantly increased compared with that of the polar lipid fraction and constituted 80% of the total at the stationary phase. The neutral and polar lipids of Microdochium nivale contained 18:3 (9,12,15), 18:2 (9,12), 18:1 (9), and 16:0 as principal fatty acids. Among them, 18:2 (9,12) and 18:3 (9,12,15) were the major fatty acids of triacylglycerol, phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine, whereas in diacylglyceryltrimethylhomoserine, the major components were 16:0 and 18:3 (9,12,15).Key words: snow mold, phospholipids, betaine lipid, fatty acid, Microdochium nivale.
Utilization of the compatible solutes sucrose and trehalose by purple sulfur and nonsulfur bacteria
Authors: Welsh David T , Guyoneaud Remy , Caumette Pierre
Published: April 2011

Owing to their ubiquity as compatible solutes, sucrose and trehalose and their constituent monosaccharides, glucose and fructose, may represent a significant source of carbon for the growth of other bacteria. We investigated sugar utilization by 34 strains of purple sulfur and nonsulfur bacteria isolated from coastal lagoons. Amongst the purple nonsulfur bacteria, sugar utilization was common with almost all strains utilizing the tested monosaccharides and 70 and 50% of strains utilizing sucrose and trehalose, respectively. Sugar utilization was rarer amongst the purple sulfur bacteria, with none of the strains using glucose or trehalose. Fructose, was utilized by 50% of isolates and sucrose was utilized only by strains of Thiorhodococcus. Surprisingly, although unable to use glucose directly, Thiorhodococcus strains used both the glucose and fructose moieties of sucrose and utilized glucose slowly in the presence of fructose, indicating that these strains may be impaired in glucose transport, rather than glucose metabolism per se. Disaccharide metabolism was dependent on sugar uptake and none of the strains produced trehalases or sucrases. Efficacy of sugar utilization varied widely with specific growth yield between 0.09 and 0.78 g dry weight·g sugar-1, and was dependent upon both the sugar and the strain. Similarly, specific growth rates were highly variable with strain and the sugar present and ranged between 5.4 and 0.5 × 10-2·h-1.Overall, data indicate that in natural high salinity ecosystems, purple sulfur and particularly purple nonsulfur bacteria may be able to efficiently exploit compatible solutes released to the environment by other members of the bacterial community.Key words: Chromatiaceae, purple sulfur bacteria, purple nonsulfur bacteria, sugar utilization.
Random amplified polymorphic DNA analysis and demonstration of genetic variability among bifidobacteria isolated from rats fed with raw kidney beans
Authors: Fanedl Lijana , Nekrep Franc V , Avgutin Gorazd
Published: April 2011

A rise in bifidobacterial numbers resembling the Escherichia coli overgrowth phenomenon was observed in the rat small intestine in a feeding experiment with kidney beans. Bifidobacterial colony counts increased from 7.6 × 106 to 1.7 × 108 cfu·g-1 of intestinal tissue in the anterior part and from less than 1 × 105 to 2.65 × 108 cfu·g-1 in posterior part of the intestine. Fifteen bifidobacterial strains were purified and further analysed. Random amplified polymorphic DNA (RAPD) assays were used to genetically differentiate bifidobacterial isolates from rat gut and compare them with type strains of 20 different species from the genus Bifidobacterium. A total of 80 arbitrary decamere primers were screened with 6 isolates, and 7 primers were chosen for the final analysis. The amplified DNA bands were scored and analysed by the unweighted pair-group method using arithmetic averages clustering. The isolates were not identical to each other nor to the screened type strains. Whereas it was possible to group 12 of the isolates into 2 separate clusters, 3 strains showed no significant relatedness to any strain. The results of the RAPD analysis indicated that there was a large degree of genetic variability among the bifidobacteria in the rat gut and demonstrated the potential applicability of such an approach in the investigation of microbial diversity in complex ecosystems.Key words: kidney bean, rat gut, RAPD, genetic variability, Bifidobacterium.
Aging of Cryptosporidium parvum oocysts in river water and their susceptibility to disinfection by chlorine and monochloramine
Authors: Chauret Christian , Nolan Kerry , Chen Ping , Springthorpe Susan , Sattar Syed
Published: April 2011

Cryptosporidium parvum oocysts were aged in waters from both the St. Lawrence River and the Ottawa River. In situ survival experiments were carried out by incubating the oocysts in either dialysis cassettes or microtubes floated into an overflow tank. A significant portion of the oocysts survived in the test waters for several weeks. Oocyst survival in the St. Lawrence River was better in membrane-filtered (0.2-µm-pore diameter) water than in unfiltered water, suggesting that biological antagonism may play a role in the environmental fate of the parasite. Oocysts aged in river waters under in situ conditions and control oocysts kept refrigerated in synthetic water (100 ppm as CaCO3; pH 7.0) were subjected to the same disinfection protocol. Aged oocysts were at least as resistant as, if not more resistant than, the control oocysts to disinfection. This indicates that the oocysts surviving in the water environment may be just as difficult to inactivate by potable water disinfection as freshly shed oocysts. Therefore, water treatment should not be based on the assumption that environmental oocysts may be more easily inactivated than freshly shed oocysts. First-order kinetics die-off rates varied from one river to another (from 0.013 to 0.039 log10·day-1) and from one experiment to another with water from the same river collected at different times. Calculation of the die-off rates based on either in vitro excystation or in vitro excystation in combination with total counts (overall die-off rates) showed that the assessment of oocyst viability by microscopic methods must account for the total oocyst loss observed during long-term inactivation assays of river waters.Key words: Cryptosporidium, survival, disinfection, biological antagonism.
Polyclonal antibodies against fusaproliferin
Authors: Monti Simona M , Fogliano Vincenzo , Randazzo Giacomino , Peluso Giuseppe , Logrieco Antonio , Ritieni Alberto
Published: April 2011

Fusaproliferin (FP), a toxic metabolite of the world-wide maize pathogens Fusarium proliferatum and Fusarium subglutinans, was recently found to be a natural contaminant of maize. Its toxic activity on haematopoietic human cell lines and its teratogenic effects on chicken embryos has been recently proved. Therefore a sensitive, rapid, and inexpensive screening test to detect FP in agricultural commodities is necessary to protect human health. FP-hemiglutarate conjugated to modified bovine serum albumin was synthesized, characterized, and used as an antigen for raising polyclonal antibodies by immunizing rabbits. Indirect and competitive ELISA and immunoblotting analyses were performed to determine antibody specificity towards the mycotoxin. The determination of 10 µg of free FP/mL was achieved using antibodies purified by means of affinity chromatography on a FP-lysine-Sepharose column. This unsatisfactory detection limit is due to high background values; thus, this method is not competitive with traditional UV-HPLC methods.Key words: fusaproliferin, ELISA, mycotoxin, immunoassay, corn, Fusarium.
pGR71 plasmid promotor sequence temporally regulated in Bacillus subtilis
Authors: Daxhelet Guy , Gilot Philippe , Nyssen Etienne , Hoet Philippe
Published: April 2011

pGR71, a composite of plasmids pUB110 and pBR322, replicates in Escherichia coli and in Bacillus subtilis. It carries the chloramphenicol resistance gene (cat) from Tn9, which is not transcribed in either host by lack of a promoter. The cat gene is preceded by a Shine-Dalgarno sequence functional in E. coli but not in B. subtilis. Deleted pGR71 plasmids were obtained in B. subtilis when cloning foreign viral DNA upstream of this cat sequence, as well as by BAL31 exonuclease deletions extending upstream from the cat into the pUB110 moiety. These mutant plasmids expressed chloramphenicol acetyltransferase (CAT), conferring on B. subtilis resistance to high chloramphenicol concentrations. CAT expression peaked at the early postexponential phase of B. subtilis growth. The transcription initiation site of cat, determined by primer extension, was located downstream of a putative promoter sequence within the pUB110 moiety. N-terminal amino acid sequencing showed that native CAT was produced by these mutant plasmids. The cat ribosome-binding site, functional in E. coli, was repositioned within the pUB110 moiety and had consequently an extended homology with B. subtilis 16S rRNA, explaining the production of native enzyme.Key words: chloramphenicol acetyltransferase, Bacillus subtilis, postexponential gene expression, plasmid pUB110, ribosome-binding site, transcriptional promoter.
Interactions between gut-associated lymphoid tissue and colonization levels of indigenous, segmented, filamentous bacteria in the small intestine of mice
Authors: Snel J , Hermsen C C , Smits H J , Bos N A , Eling WMC , Cebra J J , Heidt P J
Published: April 2011

Unlike most other indigenous bacteria, segmented filamentous bacteria (SFB) are potent activators of the mucosal immune system. SFB are strongly anchored to the epithelial cells of the small intestine where they have a preference for mucosal lymphoid epithelium. Since SFB are only present in high numbers shortly after weaning, it was investigated whether an SFB-induced immune reaction results in the removal of these bacteria from the small intestine. A correlation was found between age and colonization levels in the small intestines of SFB monoassociated Swiss mice. Five-week-old athymic BALB/c (nu/nu) mice showed lower colonization levels than their heterozygous littermates, but the opposite was found at the age of 12 weeks. However, SFB inoculation of germfree Swiss mice resulted in higher colonization levels in 5-week-old mice when compared with 4-month-old mice. We conclude that SFB colonization levels in the small intestine are likely influenced by the activity of the mucosal immune system. However, an additional age-dependent factor that modulates SFB colonization levels cannot be excluded.Key words: segmented filamentous bacteria, small intestine, gut-associated lymphoid tissue.
Changes in fecal microflora induced by intubation of mice with Bacillus subtilis (natto) spores are dependent upon dietary components
Authors: Hosoi Tomohiro , Ametani Akio , Kiuchi Kan , Kaminogawa Shuichi
Published: April 2011

We examined changes in mouse fecal microflora after various dietary components and Bacillus subtilis (natto) spores were delivered by intubation. The administration of intact spores of Bacillus subtilis (natto) did not affect fecal Enterobacteriaceae and Enterococcus spp. in all three diet groups; on the other hand, it did affect fecal Bacteroidaceae and Lactobacillus spp., depending upon the diets fed. The administration of autoclaved spores did not alter fecal microflora. In vitro cultures of Lactobacillus murinus obtained from mouse feces, together with Bacillus subtilis (natto) under aerobic conditions as a mixed culture, revealed that the growth of L. murinus was enhanced by the addition of intact spores of Bacillus subtilis (natto). This enhancement of growth was displayed only in media containing either sucrose, glucose, maltose, or fructose but not in media containing cornstarch, soluble starch, or microcrystalline cellulose. From these results it was evident that some metabolites of Bacillus subtilis (natto) produced during germination and (or) outgrowth of spores of this strain, requiring monosaccharides or oligosaccharides, participated in the enhancement of the growth of L. murinus.Key words: Bacillus subtilis (natto), Lactobacillus, probiotics, intestinal microflora, dietary components.
The replication cycle of tanapox virus in owl monkey kidney cells
Authors: Mediratta Sangita , Essani Karim
Published: April 2011

The growth kinetics of tanapox virus in owl monkey kidney cells was elucidated by single-step growth curves at multiplicities of 10, 1.0, and 0.1 plaque forming units (pfu) per cell at 37 and 33°C. Virus replicated equally well at both temperatures and produced a cytopathic effect that was characterized by densely packed rounded cells with retrogressed monolayer and granular vacuolated cytoplasm. Single-step growth curves revealed that the eclipse period varied from 24 h postinfection (hpi) at a multiplicity of infection of 10 pfu/cell to 48 hpi at 0.1 pfu/cell. The length of the latent period also varied from 36 hpi at 10 pfu/cell to 48 hpi at 0.1 pfu/cell. The intracellular virus, extracellular virus, and total virus titers reached their maximums relatively early at 10 pfu/cell as compared with 0.1 pfu/cell. About 78% of the mature progeny virion is retained intracellularly at 10 pfu/cell at 96 hpi. We conclude that tanapox virus replication is similar to other poxviruses, but the replication cycle is longer when compared with vaccinia virus.Key words: tanapox virus, single-step growth curve, eclipse period, latent period.
Genetic analysis of Aspergillus nidulans unstable transformants obtained by the biolistic process
Authors: Barcellos Fernando Gomes , Fungaro Maria Helena Pelegrinelli , Furlaneto Márcia Cristina , Lejeune Bernard , Pizzirani-Kleiner Aline A , Lúcio de Azevedo João
Published: April 2011

Mitotically unstable Aspergillus nidulans argB+ transformants obtained by the biolistic process were studied in the present work. Hybridization signals from undigested DNA and pulsed-field chromosomal bands of the transformants suggested the introduced plasmid occurred as free concatenated molecules. Fifteen vigorous growth sectors released from the transformants were analysed in order to understand the mechanisms involved in their formation. All sectors showed the integration of exogenous genes into the fungal genome by homologous or heterologous recombinant events.Key words: Aspergillus nidulans, biolistic process, mitotic instability, fungal transformation.
Snowpack recovery in regenerating coastal British Columbia clearcuts
Authors: Hudson Robert
Published: April 2011

A study was undertaken to define curves of snowpack recovery for coastal B.C. forests. The study was conducted using repeated snow course sampling techniques under regenerating stands with a range of canopy heights, and old growth. Measurements were made over five seasons from 1992-1993 to 1996-1997. For each season, recovery factors due to both peak accumulation and post-peak ablation rate were calculated for the regenerating stands. These factors were calculated using linear interpolation between extremes defined by the peak accumulation or ablation rate of old growth and clear-cut equivalent plots. An asymptotic exponential model was found to provide a reasonable fit to the data of recovery as a function of either canopy height or canopy density. The results suggest that there is a hydrologic recovery threshold at a level where the tallest trees in the stand are at a height roughly equal to the mean peak snow depth for open sites. Recovery proceeds rapidly; at a height of 4 m or canopy density of 20%, expected recovery is about 50%. At a height of 8 m, or a canopy density of 45%, expected recovery is about 75%, and by the time the trees have reached a height of 20 m, or more than 95% canopy density, the stand approaches full recovery. These results demonstrate how clear-cut harvesting and subsequent regeneration affect snow accumulation and ablation at the site level, but do not address the important issue of how those changes affect streamflow at the watershed scale.
Changes in streamwater chemistry after 20 years from forested watersheds in New Hampshire, U.S.A.
Authors: Martin C W , Driscoll C T , Fahey T J
Published: April 2011

Long-term patterns of streamwater chemistry provide valuable evidence of the effects of environmental change on ecosystem biogeochemistry. Observations from old-growth forests may be particularly valuable, because patterns should not be influenced by forest succession. Water samples were collected biweekly from four streams in, and near, the old-growth forest watershed of the Bowl Research Natural Area in the White Mountains of New Hampshire from May 1973 through October 1974, and from June 1994 through June 1997. Average NO3 concentrations, which ranged from 40.8 to 46.1 µequiv.·L-1 in 1973-1974, declined significantly to averages of 14.9-20.1 µequiv.·L-1 during 1994-1997. Concentrations of the base cations, Ca2+ and Mg2+, also declined in stream water between the two sampling periods. The northeastern United States, including the study area, has been subjected to elevated atmospheric deposition of sulfur and nitrogen for more than 40 years. This observation has led to the concern that mature forest ecosystems may exhibit N saturation and depletion of Ca2+ from exchangeable soil pools. While the Bowl exhibits a pattern of elevated concentrations of NO3 throughout the year, suggestive of conditions of N saturation, concentrations have declined markedly over the last 20 years. Concentrations of Ca2+ have also declined suggesting possible depletion from the exchangeable soil pool, but the acid neutralizing capacity of stream water has remained constant or increased, indicating resistance to additional acidification.
Effects of suppression and release on sapling growth for 11 tree species of northern, interior British Columbia
Authors: Wright Elaine F , Canham Charles D , Coates K D
Published: April 2011

Saplings of canopy tree species frequently undergo alternating periods of suppression and release before reaching canopy size. In this study, we document the effects of periods of suppression and release on current responses to variation in light by saplings of the 11 major tree species of northwestern, interior British Columbia. We were specifically interested in the degree to which increasing length of suppression had long-term effects on subsequent response to release in gaps or following partial cutting, and the degree to which the effects of suppression were ameliorated with time following release. At least some saplings of all 11 species had undergone alternating periods of suppression and release. The most shade-tolerant species generally did not show either a decline in growth over time during suppression or a gradual increase in growth at a given light level over time during release. The least shade-tolerant species exhibited significant declines in growth rate during suppression; however, in all of the species except trembling aspen (Populus tremuloides Michx.), the effects of suppression disappeared over time during release. Failure to account for the effects of past suppression and release leads to significant overestimates of the initial responses of shade-intolerant species to release. Our results suggest that competitive balances between species shift substantially over time as a result of growth history and that these shifts have significant effects on successional patterns.
Crown condition, needle mass, and sapwood area relationships of Norway spruce (Picea abies)
Authors: Eckmüllner Otto , Sterba Hubert
Published: April 2011

Crown-condition assessment, hypothesized to estimate needle losses following damage from several sources, one of which might be air pollution, suffers from the subjective notion of a standard "healthy" tree. On the other hand, the foliage biomass - sapwood area ratios are reported to depend on a number of factors, e.g., site quality, stand density, crown class, and tree ring width conductivity. The authors hypothesize that early sapwood area might help to even better estimate needle biomass of Norway spruce (Picea abies (L.) Karst.) and to help standardize crown-condition assessment. Thirty-six Norway spruce trees at two Austrian sites, from three age-classes, three crown classes, and two crown-condition classes were felled. Needle mass, cross-sectional area, sapwood area, and early sapwood area (i.e., sapwood area excluding latewood) were measured. The results of this study indicate that indeed early sapwood area is a good estimator of foliage, independent of site, age, crown class, and crown condition. The ratio between early sapwood area and cross-sectional area could be a good estimator for crown condition and thus help to standardize crown-condition assessments by different surveyors.
A direct approach to quantifying organic matter lost as a result of peatland wildfire
Authors: Turetsky M R , Wieder R K
Published: April 2011

We describe a direct approach to quantifying the amount of organic matter consumed in peatlands during a single fire event, based on differences in ash concentrations between burned peat at the surface of peat cores and underlying unburned peat. We collected six peat cores at each of two continental bog and two permafrost bog sites, 3 months after a March 1999 wildfire. Results suggest high within-site variation in the amount of organic matter burned, with no significant differences between the four peatland sites or between continental and permafrost bogs. Averaged across all sites, 2.2 ± 0.5 kg C·m2 (mean ± SE, n = 24) of organic matter was consumed as a result of this single fire, a value consistent with those in the literature.
Natural fire frequency for the eastern Canadian boreal forest: consequences for sustainable forestry
Authors: Bergeron Yves , Gauthier Sylvie , Kafka Victor , Lefort Patrick , Lesieur Daniel
Published: April 2011

Given that fire is the most important disturbance of the boreal forest, climatically induced changes in fire frequency (i.e., area burnt per year) can have important consequences on the resulting forest mosaic age-class distribution and composition. Using archives and dendroecological data we reconstructed the fire frequency in four large sectors along a transect from eastern Ontario to central Quebec. Results showed a dramatic decrease in fire frequency that began in the mid-19th century and has been accentuated during the 20th century. Although all areas showed a similar temporal decrease in area burned, we observed a gradual increase in fire frequency from the west to Abitibi east, followed by a slight decrease in central Quebec. The global warming that has been occurring since the end of the Little Ice Age (~1850) may have created a climate less prone to large forest fires in the eastern boreal forest of North America. This interpretation is corroborated by predictions of a decrease in forest fires for that region of the boreal forest in the future. A longer fire cycle (i.e., the time needed to burn an area equivalent to the study area) has important consequences for sustainable forest management of the boreal forest of eastern Canada. When considering the important proportion of overmature and old-growth stands in the landscape resulting from the elongation of the fire cycles, it becomes difficult to justify clear-cutting practices over all the entire area as well as short rotations as a means to emulate natural disturbances. Alternative practices involving the uses of variable proportion of clear, partial, and selective cutting are discussed.
Stem volume models with random coefficients for Pinus kesiya in Tanzania, Zambia, and Zimbabwe
Authors: Eerikäinen Kalle
Published: April 2011

The aim of the study was to estimate stem volume and taper models for Pinus kesiya (Royle ex Gordon). The volume function provides a simple prediction model for the stem volume. Taper models were developed for over- and under-bark diameters. The under-bark taper curve was determined with the variable-exponent taper equation, whereas the over-bark taper curve was derived from the predicted under-bark taper model using the variable-exponent form of the bark-thickness model. Because of the spatial correlation structures of the data, the general assumption of uncorrelated residuals did not hold. In addition, the models were assumed to contain random parameters that vary from stand to stand and from tree to tree. Therefore, the fixed and random parameters of the models were estimated with the generalized least squares technique. The results of the study show that the mixed models for stem volume and taper are more reliable volume and diameter predictors for P. kesiya than earlier taper and volume functions.
Two-phase approaches to point and transect relascope sampling of downed logs
Authors: Ringvall Anna , Ståhl Göran , Teichmann Vera , Gove Jeffrey H , Ducey Mark J
Published: April 2011

Point relascope sampling and transect relascope sampling were recently proposed as methods for the inventory of downed coarse woody debris. By only counting logs with a relascope device, the total length squared (with point relascope sampling) or the total length (with transect relascope sampling) of downed logs in an area can be estimated. For estimates of other variables, such as volume, additional measurements on the sampled logs are required. In this article, two-phase approaches to the methods are presented that makes use of the estimates from fast counts of logs as auxiliary data. The presented approaches serve two purposes: (i) to improve the efficiency of the methods and (ii) to avoid the bias that is likely to occur if careful checks of whether or not doubtful logs should be counted are neglected. Each two-phase design was compared with a single-phase design in terms of the standard error obtained for a given inventory cost. The two-phase designs decreased the standard errors with ca. 1718% for points and 1015% for lines. Including subjective judgements as additional auxiliary variables further decreased the standard errors in the line case but not in the point case. In the former case, the improvement in comparison with the single-phase design was 1723%.
Light-use efficiency of native and hybrid poplar genotypes at high levels of intracanopy competition
Authors: Green D Scott , Kruger Eric L , Stanosz Glen R , Isebrands J G
Published: April 2011

In southern Wisconsin, U.S.A., tree growth and associated canopy traits were compared among five native and hybrid genotypes of poplar (Populus spp.) in replicated, monoclonal stands planted at a 1 × 1 m spacing. The overall objective of this study was to assess clonal suitability to cultural conditions entailing high levels of intracanopy competition (such as high-density plantations or long rotations) and to identify selection criteria suitable to such conditions. Two of the clones were Populus deltoides Bartr., two were P. deltoides × Populus nigra L. (DN) crosses, and the fifth was a P. nigra × Populus maximowiczii A. Henry (NM) cross. In the third year after establishment, variation in aboveground biomass gain (ANBG) was analyzed in relation to canopy light interception (IPAR) and canopy light-use efficiency (LUE) during a 31-day period when growing conditions were most favorable (late June through late July). ANBG in this interval varied by twofold among genotypes (2.765.78 Mg·ha1), and it was highest in the two P. deltoides clones, followed by the NM and DN hybrids, respectively. Across genotypes, ANBG was unrelated to IPAR, which varied by only 5%. Instead, it was strongly and positively related (r2 = 0.99) to the twofold variation in LUE (1.062.22 g·MJ1). Among measured canopy traits, the best predictor of LUE (r2 = 0.88) was an additive combination of factors associated to the optimization of canopy photosynthesis: LUE was negatively related to both the canopy light-extinction coefficient and compensation irradiance at the canopy base. We infer from these findings that poplar genotypes can vary considerably in LUE and, correspondingly, in the extent to which photosynthesis is optimized in dense canopies. Furthermore, the low LUE among hybrid genotypes at this level of intracanopy competition may reflect a bias in "tree improvement" efforts towards maximizing biomass production under conditions of relatively low competition.
Early seedling growth of Pinus sylvestris after sowing with a mixture of stand and orchard seed in dense spacings
Authors: Wennström Ulfstand , Bergsten Urban , Nilsson Jan-Erik
Published: April 2011

Effects on early seedling growth of seeding stand and orchard seed of Pinus sylvestris L. in different mixtures (100, 75, 50, 25, and 0% of orchard seed) at 4-cm target spacing were quantified in one nursery and one field experiment during a 2- and 5-year period, respectively. In the field experiment, 50% mixtures at 8- and 12-cm target spacing were also studied. Seedlings from orchard seeds (OS) had in general higher growth rate than seedlings from stand seed (SS). In the nursery experiment, OS were 25% taller, had 41% larger above-soil biomass, and 18% larger root biomass than SS after 2 years when sown separately. However, root/shoot ratio was 26% less and the slenderness value (height/diameter ratio) was 11% greater for OS in comparison with SS. Stand seed in high competition, compared with low competition (mixture 75% vs. mixture 0%), were 11% taller, had 15% greater slenderness value, and 25% less root biomass after 2 years. OS had 9% greater slender value in mixture 100% compared with the 25% mixture. In the field experiment, the tallest OS in each plot were 22% taller and the largest OS had 103% larger stem volume than the tallest or largest SS when sown separately after 5 years. After a height-selection thinning to one seedling per plot at year five, 79% of the seedlings in 50% mixtures would be OS. Seedlings sown in 12-cm spacing were 69% taller and had 527% larger stem volume than seedlings in 4-cm spacing after 5 years. The investigation supports that orchard and stand seed could be direct seeded in a mixture. Low dosages of the more expensive orchard seeds could be used to obtain growth advantages. Stand seeds should be added to increase the number of seedlings to the desired spacing.
Evaluation of the importance of acclimation of needle structure, photosynthesis, and respiration to available photosynthetically active radiation in a Scots pine canopy
Authors: Palmroth S , Hari P
Published: April 2011

We analyzed the combined effect of differences in the photosynthetic light response curve and in the distributions of photosynthetically active radiation (PAR) irradiance within the canopy on the CO2 exchange rates of Scots pine (Pinus sylvestris L.) shoots. Nitrogen concentration did not vary with depth within the canopy, but leaf mass per area (LMA) ranged from 58.2 to 95.2 g·m2 (all needle age-classes pooled) and increased with increasing available PAR. The photosynthetic light response curves of 75 randomly sampled, 1-year-old shoots (with a fixed structure) were measured in the laboratory. No statistically significant differences in photosynthetic parameters or stomatal conductance either on an area or mass basis were detected between the top, middle, and bottom zones of the canopy. However, a significant decrease occurred in the area-based dark respiration rate (Rd) with increasing depth in the canopy. The area-based maximum CO2 exchange rate was weakly correlated with needle nitrogen content (Narea) and LMA, whereas Rd showed a higher correlation with both Narea and LMA. Estimates of the CO2 exchange rate over a day (24 h) in July suggest that the apparently small differences in mean light response curves of the canopy zones are reflected in the enhanced performance of shade needles in low light conditions because of reduced respiration costs. Based on our results, structural acclimation of needles along the light gradient, rather than changes in biochemical machinery, appears to be the more important acclimation process in Scots pine.
Errors in estimating tree age: implications for studies of stand dynamics
Authors: Wong Carmen M , Lertzman Ken P
Published: April 2011

Errors in estimates of tree ages from increment cores can influence age-class distributions, affecting inferences about forest dynamics. We compare methods of height correction of increment cores taken above ground level by examining how resulting errors affect age-class distributions of ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) and Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco). We compared the sapling (corrections based on the average basal age of breast high saplings) and the ground methods (corrections based on the average difference in age between ground and coring height) with a regression model we developed to overcome traditional assumptions of temporal and spatial homogeneity in early growth. Where early growth differed among mature trees or between modern saplings and mature trees, the regression method estimated age better than the two other methods. All methods of height correction over- or under-estimated tree age by at least 10 years and up to 30 years, indicating that age cannot be related to independent events of periodicities less than 1020 years, such as El Niño, without accounting for error. Monte Carlo simulations demonstrated that error from height corrections affected the shape of age-class distributions by generating spurious regeneration pulses. We suggest that the magnitude of this error should govern the width of analytical age-classes to scale interpretations within the confidence of age estimates.