bluuebunny/crossref_metadata_2025 huggingface dataset:
Mouse genetic model for left-right hand usage: Context, direction, norms of reaction, and memory
Authors: Biddle Fred G , Eales Brenda A
Published: April 2011

Asymmetry of paw usage in the laboratory mouse is an experimental model for left-right asymmetry of hand usage. Given a set number of reaches into a centrally placed food tube (an unbiased or U-world test), individual mice exhibit a number of left and right paw reaches that is reliably expressed on retesting. Whereas different inbred strains appear to have equal numbers of individual mice with a left- or a right-preferred paw after a U-world test, there are significant differences among strains in the degree or strength of lateralization of the preferred paw. We report here a systematic series of tests of paw usage with naive mice and retests of the individuals in test chambers with the food tube biased to the left or to the right, contrasting the highly lateralized C57BL/6J and the very weakly lateralized (or ambilateral) CDS/Lay inbred strains and their (B6 × CDS) F1 generation. The results caused a shift in the paradigm of paw usage. There is an unexpected qualitative difference in paw usage between C57BL/6J and CDS/Lay. C57BL/6J is random in its left-right paw usage, but it is conditioned by the left or right direction of the initial biased-world test and by usage. CDS/Lay is constitutively equal-pawed, responds very little to direction of the test chamber, and is not conditioned by it. The probability of left-paw versus right-paw usage depends on both the genotype and the context of the test. The (B6 × CDS) F1 generation suggests that constitutive equal-paw usage of CDS/Lay is dominant to experience-conditioned paw usage of C57BL/6J. There is also an apparent quantitative difference between the very weakly lateralized (ambilateral) preferred paw usage in CDS/Lay and the highly lateralized preferred paw usage in C57BL/6J. The difference in degree of lateralization of preferred paw usage between the constitutively equal-pawed CDS/Lay strain and (B6 × CDS) F1 generation must originate from allelic differences at other gene loci between the CDS/Lay and C57BL/6J parental strains. The SWV and NOD/Lt strains were also assessed in asymmetrical tests because they were known to be weakly lateralized and similar to each other in a U-world test and to be significantly different from both C57BL/6J and CDS/Lay. SWV is experience-conditioned and weakly lateralized; NOD/Lt is constitutively equal-pawed and weakly lateralized. Further analysis will determine the genetic cause of the qualitative difference between constitutive equal-paw and experience-conditioned paw usage and the genetic cause of the quantitative differences in degree of lateralization of the preferred paw within each type of paw usage.Key words: mouse, left-right handedness, behavioural genetics, phenotypic reaction norms, constitutive behaviour, experience-conditioned behaviour, memory.
Use of microsatellite DNA markers to investigate the level of genetic diversity and population genetic structure of coconut (Cocos nucifera L.)
Authors: Perera L , Russell J R , Provan J , Powell W
Published: April 2011

We have used eight pairs of simple sequence repeat (SSR) primers to analyse the genetic diversity in 130 individuals of coconut (Cocos nucifera L.) comprising 75 tall individuals and 55 dwarf individuals, representing 94 different coconut ecotypes throughout the world. A total of 51 alleles were detected, with an average of 6.4 alleles per locus. Fifty alleles were detected in tall coconuts (talls; mean alleles/locus 6.3) compared with only 26 (mean/ locus 3.3) in dwarfs, and the average diversity value in talls (0.589) was also significantly higher than that in dwarfs (0.348). Using the eight SSRs we were able to uniquely discriminate 116 of the 130 individuals. A phenetic tree based on DAD (absolute distance) values clustered individuals into five groups, each mainly composed of either talls or dwarfs. These results provide evidence in support of previous hypotheses concerning the dissemination of coconut, as well as important new information for conservation and breeding purposes. Key words: coconut, Cocos nucifera, microsatellites, SSR, genetic diversity.
Tirantis a new member of thegypsyfamily of retrotransposons inDrosophila melanogaster
Authors: Cañizares J , Grau M , Paricio N , Moltó MD
Published: April 2011

In this paper, we propose a consensus sequence for a putative complete Tirant retrotransposon. Several defective copies, as well as relevant sequences available in databases have been analyzed. The putative complete Tirant element is 8533 bp long, and presents all the structural features of a retroviruslike transposable element of the gypsy family. It contains three ORFs (open reading frames) that encode putative products resembling the retroviral Gag, Pol, and Env proteins. Southern blot analyses show that complete and defective Tirant elements are widespread in Drosophila melanogaster. The different hybridization patterns observed in several natural populations of this species suggest that Tirant is an active element. Key words: Drosophila, LTR-retrotransposon, gypsy, retrovirus, envelope protein, phylogeny.
Tandem repetitive Afa-family sequences from Leymus racemosus and Psathyrostachys juncea (Poaceae)
Authors: Nagaki Kiyotaka , Kishii Masahiro , Tsujimoto Hisashi , Sasakuma Tetsuo
Published: April 2011

Tandem repetitive Afa-family sequences of 340 bp are known to occur in wheat and related species of tribe Triticeae. We isolated six and three Afa-family sequences from Leymus racemosus and Psathyrostachys juncea, respectively, both of which are perennial species. The sequences account for 0.5% and 0.2% of L. racemosus and P. juncea genomes, respectively, and using in situ hybridization were located in subtelomeric and interstitial regions of L. racemosus chromosomes. These sequences are clustered with those of Elymus trachycaulus in the phylogenetic tree. Our findings indicate that the Afa-family sequences have been amplified at least twice in the lineage of L. racemosus, P. juncea, and E. trachycaulus.Key words: Triticeae, Leymus, Psathyrostachys, tandem repeat, Afa-family sequences.
Development of SCAR markers to the PVY resistance gene Ryadg based on a common feature of plant disease resistance genes
Authors: Kasai K , Morikawa Y , Sorri V A , Valkonen JPT , Gebhardt C , Watanabe K N
Published: April 2011

Sequence-characterized amplified regions (SCARs) were developed, based on nucleotide differences within resistance gene-like fragments isolated from a potato plant carrying the Ryadg gene, which confers extreme resistance to potato Y potyvirus (PVY). It originates from Solanum tuberosum subsp. andigena, and a susceptible potato plant. SCARs were tested using 103 potato breeding lines and cultivars with diverse genetic backgrounds derived from Europe, North America, and Japan. Two markers showed high accuracy for detection of the Ryadg gene. The SCAR marker RYSC3 was generated only in genotypes carrying Ryadg. The SCAR marker RYSC4 was detected in all genotypes carrying Ryadg but also in four PVY-susceptible genotypes. Neither marker was detected in genotypes carrying other Ry genes originating from different species than S. tuberosum subsp. andigena. Therefore, these SCAR markers should be powerful tools in marker-assisted selection for Ryadg in potato breeding programs, and should also be useful for cloning of the Ryadg gene. Key words: SCAR, potato virus Y, extreme resistance gene, Solanum.
Chloroplast microsatellite analysis reveals the presence of population subdivision in Norway spruce (Picea abiesK.)
Authors: Vendramin G G , Anzidei M , Madaghiele A , Sperisen C , Bucci G
Published: April 2011

Three chloroplast microsatellites (cpSSRs), previously sequence characterized and for which paternal inheritance was tested and confirmed, were used to assess their usefulness as informative markers for phylogeographic studies in Norway spruce (Picea abies K.) and to detect spatial genetic differentiation related to the possible recolonization processes in the postglacial period. Ninety-seven populations were included in the survey. Some 8, 7, and 6 different size variants for the three cpSSRs, respectively, were scored by analysing 1105 individuals. The above 21 variants combined into 41 different haplotypes. The distribution of some haplotypes showed a clear geographic structure and seems to be related to the existence of different refugia during the last glacial period. The analysis of chloroplast SSR variation detected the presence of two main gene pools (Sarmathic-Baltic and Alpine - Centre European) and a relatively low degree of differentiation (RSTof about 10%), characteristic of tree species with large distribution and probably influenced by an intensive human impact on this species. Based on our data, we were not able to detect any evidence concerning the existence of additional gene pools (e.g., from Balkan and Carpathian glacial refugia), though we cannot exclude the existence of genetic discontinuity within the species' European range. A large proportion of population-specific haplotypes were scored in this species, thus indicating a possible usefulness of these markers for the identification of provenances, seed-lots, and autochthonous stands. Key words: haplotypic diversity, phylogeography, chloroplast microsatellites, recolonization.
Variability in rDNA loci in Iberian species of the genus Zabrus (Coleoptera: Carabidae) detected by fluorescence in situ hybridization
Authors: Sánchez-Gea JF , Serrano J , Galián J
Published: April 2011

Fluorescence in situ hybridization (FISH) with a PCR-amplified 18S ribosomal probe was used to map rDNA loci in 19 taxa of the ground beetle genus Zabrus (2n = 47-63) from the Iberian Peninsula. A quantitative and qualitative variation has been observed among related species, subspecies, populations, and even individuals. The number of rDNA-carrying chromosomes varies from 2 to 12, and the extent of the signal from small dots to entire arms. Changes altering the number of rDNA clusters seem to be uncoupled from the variation found in the chromosome number. Mechanisms that explain the numerical variation and spreading of rDNA clusters throughout the genome within the genus Zabrus are briefly discussed. No concordance between the pattern of rDNA sites and the phylogenetic relationships as based on morphological characters has been found. Key words: Carabidae, Coleoptera, fluorescence in situ hybridization, polymorphism, ribosomal DNA, Zabrus.
The 5S rRNA gene diversity in Kengyilia rigidula (Keng and S.L. Chen) J.L. Yang, Yen, and Baum (Poaceae: Triticeae): Possible contribution of the H genome to the origin of Kengyilia
Authors: Baum Bernard R , Bailey L Grant
Published: April 2011

Fifty-three units of 5S rDNA sequences from five accessions of Kengyilia rigidula, a member of the tribe Triticeae that also includes wheat, barley, rye, and their wild relatives, have been amplified by the polymerase chain reaction (PCR), cloned, and sequenced. The genome of K. rigidula consists of three haplomes, St, P, and Y. An evaluation of the aligned sequences of the diverse 53 different 5S DNA units yielded three 5S-unit classes. One unit class, Long S1, was assignable to the St haplome, one unit class, the Long P1, was assignable to the P haplome, and a third unit class, Long H1, was assignable to the H haplome. The last was expected to be assignable to the Y haplome, based on previous knowledge. Evolutionary scenarios are put forward to explain this finding. Among those possibilities is that the number of copies of units assignable to the Y haplome is very small and difficult to detect. Short units, reported earlier in K. alatavica, were not found in K. rigidula. Key words: 5S RNA gene, genomes, Triticeae, 5S DNA unit classes.
A binary vector-based large insert library forBrassica napusand identification of clones linked to a fertility restorer locus forOguracytoplasmic male sterility (CMS)
Authors: Wu Yongzhong , Tulsieram Lomas , Tao Quangzhou , Zhang Hong-Bin , Rothstein Steven J
Published: April 2011

We constructed and characterized a large DNA insert library for Brassica napus that would facilitate genome-related research and map-based cloning efforts in Brassica species. This library, consisting of 92 160 clones arrayed in 384-well microtiter dishes, was based on a conventional plant transformation vector (binary vector), and was constructed using a single ligation with transformation efficiency of over 5000 recombinants per microliter of ligation mixture. Every clone in this library contains an insert in the size range of 30-190 kb, facilitating both chromosome walking and plant transformation. Screening this library with three DNA markers (C2, F10, and CabR) that are linked to a fertility restorer locus for Ogura cytoplasmic male sterility (CMS) identified at least 17 positive clones for each probe. Among the 17 positive clones identified by C2, nine are linked to the restorer locus. Marker F10 identified 21 clones, of which only two are linked to the restorer locus. None of 68 clones identified by CabR is linked to the restorer locus. A stability test using two clones identified by the C2 marker indicated that large DNA inserts are stable in this conventional vector in both Escherichia coli and Agrobacterium. Key words: Brassica napus, binary vector, large DNA insert library, restorer gene.
Combined AFLP and RFLP mapping in two hexaploid oat recombinant inbred populations
Authors: Jin Hua , Domier Leslie L , Shen Xuejen , Kolb Frederic L
Published: April 2011

A combined RFLP and AFLP map was constructed for hexaploid oat (Avena spp.). The segregation of AFLP markers was scored in two hexaploid oat recombinant inbred line (RIL) populations, the 'Kanota' × 'Ogle' RFLP population, and a population derived from 'Clintland64' and 'IL86-5698', barley yellow dwarf virus (BYDV)-sensitive and BYDV-tolerant lines, respectively. More than 300 AFLP markers were scored in each population, of which 97 could be scored in both populations. AFLP markers were linked to RFLP markers in 32 of 36 'Kanota' × 'Ogle' RFLP linkage groups. The addition of the AFLP markers to the 'Kanota' × 'Ogle' RFLP data set combined markers from four pairs of linkage groups and increased the size of the map from 1402 cM to 2351 cM. Thirty linkage groups were observed in the 'Clintland64' × 'IL86-5698' population, two of which could be consolidated by comparing the maps from both populations. The AFLP and RFLP markers showed very similar distributions in the 'Kanota' × 'Ogle' population with a tendency of each type of marker to cluster with markers of the same type. The placement of a set of AFLP markers on the 'Kanota' × 'Ogle' linkage map will enrich the RFLP map and allow others to relate AFLP markers for agronomically important genes to the reference 'Kanota' × 'Ogle' linkage map. Key words: amplified fragment length polymorphism, Avena, comparative mapping.
Characterization of university-level introductory genetics courses in Canada
Authors: Haffie Thomas L , Reitmeier Yvonne M , Walden David B
Published: April 2011

We conducted survey research with the intent to characterize post-secondary introductory genetics (IG) education in Canada during the 1996-1997 academic year. At least a minimum data set was obtained from 47 institutions through responses to a mailed questionnaire and on-line resources. The total reported enrollment (TRE) for IG was 10 500. Over half of the TRE used one particular text. A core curriculum of topics was identified as those given more than 30 min of lecture time in at least half of reporting institutions. Slightly more than half of the TRE had laboratory exercises associated with their IG course. Laboratory exercises tended to emphasize classical transmission genetics with very few exercises in molecular genetics. For the determination of academic equivalency between institutions, particular attention should be given to the breadth and duration of the tutorial and (or) laboratory components. The majority of personnel teaching IG were trained in Canada within the previous 15 years. We suggest mechanisms by which the Genetics Society of Canada could work to promote genetical literacy. Key words: teaching, education, curriculum.
Genome size variation in Arachis hypogaea and A. monticola re-evaluated
Authors: Temsch Eva M , Greilhuber Johann
Published: April 2011

Genome size variation within species is a frequently reported, but still a controversial problem. In the present study, we re-evaluated recently published Feulgen densitometric data on genome size and its infraspecific variation in Arachis hypogaea, and also conducted measurements in one accession of its wild relative A. monticola. The methods applied were propidium iodide flow cytometry and Feulgen densitometry using Pisum sativum as an internal standard. The 2C DNA contents previously published cannot be confirmed, but values obtained in this study are about half as large. Additionally, we could not reproduce the previously reported 1.15-fold variation within A. hypogaea; our data indicate genome size stability between respective accessions of this species. Based on 8.84 pg (2C) for Pisum sativum the DNA amounts (2C) were: 5.914 pg in A. hypogaea, and 5.979 pg in A. monticola.Key words: Arachis, genome size, flow cytometry, Feulgen densitometry.
Isolation, characterizaton, and inheritance of microsatellite loci in alpine larch and western larch
Authors: Khasa P D , Newton C H , Rahman M H , Jaquish B , Dancik B P
Published: April 2011

Microsatellite loci or simple sequence repeat loci (SSRs) were isolated in alpine larch (Larix lyallii Parl.) and western larch (Larix occidentalis Nutt.). In total, 14 SSR loci were characterized; two [(TCT)4, A7] came from published Larix DNA sequence data, one (CA)17was obtained from a partial non-enriched alpine larch total genomic DNA library, and the remaining 11 loci were obtained from larch genomic DNAs enriched for (CA)nrepeats. The SSR regions in these clones could be divided into three categories: perfect repeat sequences without interruption, imperfect repeat sequences with interruption(s), and compound repeat sequences with adjacent tandem simple dinucleotides. Eight of the 14 loci analyzed were found to be polymorphic and useful markers after silver-staining polyacrylamide gel electrophoresis. In addition, several SSR primers developed for alpine larch were able to successfully amplify polymorphic loci in its related species, western larch, and among other closely related taxa within the Larix genus. The inheritance of microsatellite loci was verified by analysis of haploid megagametophyte and diploid embryo tissues of progeny obtained from controlled crosses between western larch and alpine larch. All microsatellite loci analyzed had alleles that segregated according to expected Mendelian frequencies. Two species-specific markers (UAKLly10a and UAKLla1) allow easy and rapid identification of specific genetic entry of alpine larch and western larch at any stage in the sporophyte phase of the life cycle. Therefore, these markers are efficient in identifying the parental species and to validate controlled crosses between these two closely related species. These results are important in tree improvement programs of alpine larch and western larch aimed at producing genetically improved hybrid stock for reforestation in Western Canada and U.S.A.Key words: database search, enriched library, inheritance, Larix, microsatellites, simple sequence repeats, PCR.
Sequence conservation and expression of theSex-lethalhomologue in the flyMegaselia scalaris
Authors: Sievert Volker , Kuhn Sylvia , Paululat Achim , Traut Walther
Published: April 2011

Sex-lethal (Sxl) is Drosophila melanogaster's key regulating gene in the sex-determining cascade. Its homologue in Megaselia scalaris, the chromosome 3 gene Megsxl, codes for a protein with an overall similarity of 77% with the corresponding D. melanogaster sequence. Expression in M. scalaris, however, is very unlike that in D. melanogaster. Megsxl transcripts with a long ORF occur in both sexes. Differential splicing is conserved but not sex-specific. There are several splice variants, among them one is common to gonads and somatic tissues of all developmental stages investigated, one is specific for ovaries and embryos, and a third one is not found in ovaries. In the ovary, Megsxl is heavily transcribed in nurse cells and transported into eggs. These results suggest a non-sex-determining function during early embryogenesis; the presence of Megsxl RNA in testes and somatic tissues calls for other (or more) functions.

Key words: sex determination, RNA-binding domain, differential splicing, RNA in situ hybridization.
Identification and chromosomal localization of a transcriptionally active retrotransposon of Ty3-gypsy type in rice
Authors: Li Zi-Yin , Chen Shou-Yi , Zheng Xian-Wu , Zhu Li-Huang
Published: April 2011

A DNA fragment representing a transcriptionally active retrotransposon of Ty3-gypsy type was isolated and characterized from rice (Oryza sativa L.). The fragment (named RIRE9) includes the coding sequences for the C-terminal part of the RNase H domain and the N-terminal part of the integrase domain in the polyprotein region. Northern blot hybridization indicated that this element was expressed in rice leaves and stems, suggesting that it is potentially active to transpose under normal growth conditions. Using dot-blot hybridization, the copy number of RIRE9 was estimated to be about 1600 copies per haploid rice genome. Five homologous copies of RIRE9 were assigned to five distinct positions of four chromosomes by restriction fragment length polymorphism (RFLP) mapping approach using an indica-japonica rice doubled-haploid (DH) population and its molecular linkage map.

Key words: Oryza sativa L., Ty3-gypsy-like retrotransposon, copy number, chromosomal location.
Organization, nucleotide sequence, and chromosomal mapping of a tandemly repeated unit containing the four core histone genes and a 5S rRNA gene in an isopod crustacean species
Authors: Barzotti Rita , Pelliccia Franca , Bucciarelli Elisabetta , Rocchi Angela
Published: April 2011

A tandemly repeated unit of 6553 bp containing a copy of the four core histone genes H2B, H2A, H3, and H4, and also a 5S rRNA gene, was amplified by PCR from genomic DNA of the isopod crustacean Asellus aquaticus. The linkage between 5S rRNA genes and histone genes has been so far observed in only one other organism, the anostrac crustacean Artemia salina. The gene cluster was cloned and sequenced. The histone genes, in their 3' flanking region, have the interesting feature of possessing two different mRNA termination signals, the stem-loop structure and the AATAAA sequence. A part of the PCR product was used as a probe in FISH experiments to locate the gene cluster on an inter-individually variable number of chromosomes from 6 to 12 per diploid cell, always in a terminal position and never associated with the heterochromatic areas. Fluorescence in situ hybridization (FISH) was also performed on preparations of released chromatin and the reiteration level of the gene cluster was determined as approximately 200-300 copies per haploid genome.

Key words: Asellus, Isopoda, Crustacea, histone genes, 5S rRNA gene.
Phagocytic specificity during sexual development in Dictyostelium discoideum
Authors: Lewis Keith E. , O'Day Danton H.
Published: April 2011

During the sexual cycle of Dictyostelium discoideum, zygote giant cells develop and serve as foci for further development by chemoattracting and cannibalizing hundreds of local amoebae. Previous work has shown that the phagocytic process bears similarities to and differences from asexual endocytosis. In the present study, sexual phagocytosis in D. discoideum was found to be species and developmental stage specific. It was inhibited selectively by glucose and concanavalin A. Although a partial, inhibitory effect of mannose on phagocytosis was not statistically significant, alpha-methylmannosamine, like alpha-methyl-glucose, significantly restored the phagocytic competence of giant cells treated with concanavalin A. Other sugars (N-acetyl glucosamine, N-acetylgalactosamine, and galactose) and lectins (wheat germ agglutinin, Ulex europus type I, and Ricinis communis agglutinin type I) had no significant effect on sexual phagocytosis. Together these data indicate that a glucose-type receptor is involved in selective uptake of D. discoideum amoebae by giant cells.
Evidence for the presence of a novel biosynthetic pathway for norspermidine in Vibrio
Authors: Yamamoto Shigeo , Hamanaka Kazuya , Suemoto Yasuo , Ono Bun-ichiro , Shinoda Sumio
Published: April 2011

Enzymatic studies of the cell extracts of Vibrio alginolyticus and V. parahaemolyticus provided evidence that there exists a novel biosynthetic pathway for norspermidine (NH2(CH2)3NH(CH2)3NH2), a major polyamine species. In this pathway, the Schiff base formed between aspartic β-semialdehyde and 1,3-diaminopropane is first reduced by a NADPH-dependent enzyme to yield "carboxynorspermidine" (NH2(CH2)3NH(CH2)2CH(NH2)COOH), which is in turn decarboxylated by a pyridoxal phosphate dependent enzyme to form norspermidine. The end product and its intermediate were identified by gas chromatography–mass spectrometry. Experiments with L-[U-14C]aspartic acid resulted in appreciable incorporation of the label into norspermidine. Putrescine could replace 1,3-diaminopropane as a substrate to produce spermidine, but at a reduced rate. The enzyme activity was greatly enhanced by dithiothreitol. Since the activity of an aminopropyltransferase that utilizes decarboxylated S-adenosylmethionine as an aminopropyl group donor could not be detected in any of the cell extracts by our assay method, it was concluded that this novel pathway is primarily responsible for producing norspermidine and spermidine in these species.
Listeria monocytogenes dans le lait pasteurisé
Authors: Garayzábal J. F. Fernández , Rodríguez L. Domínguez , Boland J. A. Vázquez , Cancelo J. L. Blanco , Fernández G. Suárez
Published: April 2011

An haemolytic Listeria monocytogenes strain pathogenic to mice was isolated from 6 out of 28 (21.4%) pasteurized milk samples (3.2% fat milk treated at 78 °C for 15 s) marketed by a Madrid processing plant. Listeria grayi was recovered from 25 of the samples (89.2%) and L. innocua from 3 samples (10.7%). One milk sample was contaminated with L. welshimeri. No strains of L. ivanovii, L. seeligeri, L. murrayi, or L. denitrificans were isolated. These results show that pathogenic Listeria strains can be isolated from pasteurized milk and reinforce the hypothesis that this food product may be the source of numerous human listeriosis. [Translated by the journal]
Purification and properties of an acid proteinase from Choanephora cucurbitarum
Authors: Balasubramanian R. , Manocha M. S.
Published: April 2011

An acid proteinase has been purified from mycelial extracts of Choanephora cucurbitarum by treatment with ammonium sulphate, gel filtration, hydroxyapatite adsorption, and affinity chromatography. The enzyme hydrolysed haemoglobin rapidly compared with casein, bovine albumin, cytochrome c, and hide powder azure, but failed to hydrolyse any of the synthetic peptides tested. The acid proteinase is a glycoprotein with an apparent molecular weight of 12 700. Optimal hydrolysis of haemoglobin by the proteinase was observed at 20 °C, pH 3.0, and has a Km value of 2.8 mg∙mL−1. Heavy metallic ions, such as Hg2+, Fe2+, and Zn2+, inhibited the hydrolytic activity, whereas Ca2+ and Cu2+ enhanced the enzyme activity by two- and four-fold, respectively, as compared with the controls. Benzamidine and phenylmethanesulfonyl fluoride inhibited severely the enzyme activity, while diisopropyl fluorophosphate, antipain, N-α-p-tosyl-L-lysine chloromethyl ketone inhibited moderately. Phenylmethanesulfonyl fluoride inhibition could be reversed by 2-mercaptoethanol. Reducing agents such as cysteine and dithiothreitol did not enhance the enzyme activity. The data presented suggest that the enzyme has the characteristics of serine proteinases.
The binding of Pseudomonas aeruginosa outer membrane ghosts to human buccal epithelial cells
Authors: Doig P. , Franklin A. L. , Irvin R. T.
Published: April 2011

The binding of outer membrane (OM) ghosts derived from Pseudomonas aeruginosa strain 492c to human buccal epithelial cells (BECs) was examined. Electron microscopic examination of the binding of OM ghosts to BECs revealed direct OM ghost–BEC interaction. Equilibrium analysis of the binding of OM ghosts to trypsinized BECs employing the Langmuir adsorption isotherm indicated the number of binding sites (iV) to be 1.3 × 10−1 μg protein per BEC with an apparent association constant (Ka) of 3.4 × 10−2 mL/μg protein. The Langmuir analysis of binding of OM ghosts to untrypsinized BECs was complex, suggesting two possible classes of receptors, a high affinity–low copy number class (Ka, 1.8 × 10−2 mL/μg protein; N, 8.6 × 10−5 μg protein per BEC) and a low affinity – high copy number class(Afa, 3.7 × 10−3 mL/μg protein; N, 9.2 × 10−4 μg protein per BEC). Sugar inhibition studies incorporating D-galactose enhanced binding to each BEC type. N-Acetylneuraminic acid and N-acetyl-glucosamine both enhanced binding of OM ghosts to untrypsinized BECs, while inhibiting binding to trypsinized BECs. D-Arabinose inhibited binding to both BEC types. Binding of OM ghosts to both BEC types was greatly inhibited by D-fucose, while L-fucose only greatly inhibited binding to untrypsinized BECs. These sugar inhibition data demonstrated a difference in the binding of OM ghosts to trypsinized and untrypsinized BECs and possibly reveal the nature of the receptor(s), free of possible bacterial metabolic effects. These data indicated that OM ghosts from 492c appear to bind to BECs in a similar manner to the intact bacteria and represent a simple model system to study the adhesion of P. aeruginosa to BECs.
Stabilization and purification of the secondary metabolism specific enzyme, m-hydroxybenzylalcohol dehydrogenase
Authors: Scott Richard E. , Lam K. S. , Gaucher G. M.
Published: April 2011

m-Hydroxybenzylalcohol dehydrogenase (EC 1.1.1.97), a secondary metabolism associated protein from stationary phase cultures of Penicillium urticae, was stabilized in crude extracts prior to purification. Stabilization studies resulted in the formulation of an optimal cell breakage and purification buffer. This buffer increased the enzyme's in vitro half-life at 30 °C from 14 to over 800 min which greatly aided purification and enhanced yields. Purification was achieved by salt fractionation, size-exclusion chromatography, affinity chromatography, and ion-exchange chromatography. The 1200-fold purified protein gave only one major band by sodium dodecyl sulphate – polyacrylamide gel electrophoresis.
A comparison of the multigroup and collocation methods for solving the low-energy neutron Boltzmann equation
Authors: Clowdsley M S , Heinbockel J H , Kaneko H , Wilson J W , Singleterry R C , Shinn J L
Published: April 2011

A low-energy neutron transport algorithm for use in space-radiation protection is developed. The algorithm is based upon a multiple energy group analysis of the straight ahead Boltzmann equation utilizing a mean value theorem for integrals. The algorithm developed is then verified by using a collocation method solution on the same straight ahead Boltzmann equation. This algorithm was then coupled to the existing NASA Langley HZETRN (high charge and energy transport) code through the evaporation source term. Evaluation of the neutron fluence generated by the February 23, 1956 solar particle event for an aluminum-water shield-target configuration is then compared with the LAHET Monte Carlo calculation for the same shield-target configuration. The algorithm developed showed a great improvement in results over the unmodified HZETRN solution. A bidirectional modification of the evaporation source produced further improvement of the fluence.

PACS Nos.; 87.50N, 25.40D, 28.20G
I. Geometrical optics of variable-frequency light rays:Theoretical basis
Authors: Chyla W T
Published: April 2011

A variable-frequency light ray (VF ray) is a new concept in optics; it is a ray that is monochromatic at every point of the path (no frequency spread) but its frequency changes along the path due to interactions occurring along that path. For example, the frequency of the light ray can be affected by gravitational time dilation, reflection from a moving mirror, or coherent Raman scattering. Since the Fermat principle of least time (PLT) implicitly assumes that the frequency of the light ray is an irrelevant constant, the PLT-based geometrical optics is insufficient to handle propagation of VF rays. In this paper, we derive a new extremum principle (NEP) that is sensitive to changes of frequency along the path of the light ray and constitutes a basis for geometrical optics of VF rays. The NEP is derived directly from the principle of least action applied to the quantized electromagnetic field associated with the light ray propagating in a vacuum or in a transparent material medium in the presence of the gravitational field. The relationship between the NEP, the classical version of the Fermat principle, and the general relativistic generalization of the Fermat principle (the extremum principle for null geodesics) is discussed in detail. Applications of the NEP are suggested in the nonrelativistic, special relativistic, and general relativistic regimes. PACS Nos.: 42.15-i, 12.20-m, 04.20-q
Inverse Raman scattering and the 3 dB noise limit of a fiber Raman amplifier
Authors: Stolen R H
Published: April 2011

The fundamental 3 dB noise limit of a fiber Raman amplifier can be understood by a combination of RamanStokes gain from zero point fluctuations of the electromagnetic field, anti-Stokes absorption, and Stokes and anti-Stokes generation by zero-point fluctuations of the glass.PACS NO.: 42.55Ye
High-resolution Raman spectroscopy of gases and the determination of molecular bond lengths
Authors: Jones W J
Published: April 2011

This review highlights the developments that have taken place in the field of high-resolution Raman spectroscopy of gases from the pioneering studies of Stoicheff and Welsh in the early fifties to the present day. This period has seen major changes in the methods that have been employed for investigating pure rotation and vibration-rotation spectra from these initial studies with Hg excitation through to the deployment of laser sources for incoherent Raman scattering at enhanced sensitivity, and the subsequent development of the techniques of nonlinear Raman spectroscopy at resolutions of ~10-3 cm-1. A central theme in this review is the measurement of accurate rotational constants for nonpolar molecules that have then been employed for the determination of molecular geometries and bond lengths. The studies by Stoicheff of the pure rotational spectra of a wide range of linear and symmetric-top molecules provided an extensive data base that served to supplement bond-length determinations from other methods and enabled him to correlate CC and CH bond length variations in noncyclic compounds with changes in their environment. The discovery of laser sources in the sixties provided exciting new opportunities for the examination of pure rotation and vibration-rotation spectra at enhanced resolution and sensitivity and broadened dramatically the scope of the field. Apart from the improvements in the incoherent scattering methods afforded by these new sources, the discovery of a range of new nonlinear Raman phenomena, a field in which Stoicheff made equally important contributions, led to the creation of a range of new coherent nonlinear Raman methods that have been widely employed for the study of all rotor classes. Representative examples of the many investigations performed with the various spectroscopic methods over this period are given, together with the results of the structure determinations achieved from the analyses of the rotational spectra.PACS Nos.: 33.20Fb, 36.20.Hb
Strong localization of light and photonic atoms
Authors: Rand S C
Published: April 2011

In the strong localization regime, light confined to a well-defined volume of space by the mutual interference of its countless constituent scattered waves can be expected to acquire unusual characteristics. These include a vanishing momentum, an effective tensorial rest mass, and "photonic atom recoil." Impurity atoms that emit light under these conditions should consist of coupled atom-cavity systems with energy densities extending over regions larger than the atoms, but smaller than a cubic wavelength, in which radiant transport is suppressed by near-field correlated scattering. This unusual regime is now accessible over broad wavelength ranges in random nanoparticle media, opening the way to studies of novel phenomena such as strong localization phase transitions, lasers without cavities, and optical energy storage. PACS Nos.: 78.45+h, 78.60Hk, 42.55Rz, 42.25Fx, 78.35+c, 78.20Dj, 42.50Gy
Characteristics of the total disintegration of AgBr nuclei by 24Mg and 32S nuclei at 4.5 A GeV/c
Authors: Abd-Allah N N
Published: April 2011

The interactions of 4.5 A GeV/c 24Mg and 32S nuclei with emulsion were studied. The experimental inelastic mean free path for these interactions is compared with theoretically calculated values. The average multiplicities of the emitted secondary charged particles for total disintegration were investigated. Total disintegration events are analysed to investigate the characteristics of secondary charged particles produced in such collisions. The results show that the multiplicity distributions of relativistic charged particles agree with the Gaussion distribution. The average multiplicity of grey and black particles is in good agreement with the prediction of the fireball model. The probabilty of total disintegration of Ag(Br) nuclei by different projectiles is nearly independent of the incident energy. PACS No.: 25.70
Ground-state analysis of the Falicov-Kimball model on complete graphs
Authors: Bolina O , Marchetti D HU
Published: April 2011

The ground-state nature of the FalicovKimball model of mobile electrons and fixed nuclei on complete graphs is investigated. We give a pedagogic derivation of the eigenvalue problem and present a complete account of the ground-state energy both as a function of the number of electrons and nuclei and as a function of the total number of particles for any value of interaction U [Formula: see text] [Formula: see text]. We also study the energy gap and show the existence of a phase transition characterized by the absence of gap at the half-filled band for U < 0. The model in consideration was proposed and partially solved by Farkasovsky for finite graphs and repulsive on-site interaction U > 0. Contrary to his proposal, we conveniently scale the hopping matrix to guarantee the existence of the thermodynamic limit. We also solve this model on bipartite complete graphs and examine how sharp the KennedyLieb variational estimate is as compared with the exact ground state. PACS Nos.: 71.2-b, 02.10Gd
On classical and quantum harmonic potentials
Authors: Mohazzabi P
Published: April 2011

To date, the only potential energy function that has been demonstrated to be classical harmonic but not quantum harmonic is that of the asymmetrically matched harmonic oscillator. By investigating the accurate quantum mechanical energy levels of the potential V = V0 [Formula: see text], we demonstrate that this is the second member of the class.

PACS No.: 03.65Ge
Energy and time as conjugate dynamical variables
Authors: Grigorescu M
Published: April 2011

The energy and time variables of the elementary classical dynamical systems are described geometrically, as canonically conjugate coordinates of an extended phase-space. It is shown that the Galilei action of the inertial equivalence group on this space is canonical, but not Hamiltonian equivariant. Although it has no effect at a classical level, the lack of equivariance makes the Galilei action inconsistent with the canonical quantization. A Hamiltonian equivariant action can be obtained by assuming that the inertial parameter in the extended phase-space is quasi-isotropic. This condition leads naturally to the Lorentz transformations between moving frames as a particular case of symplectic transformations. The limit speed appears as a constant factor relating the two additional canonical coordinates to the energy and time. Its value is identified with the speed of light by using the relationship between the electromagnetic potentials and the symplectic form of the extended phase-space.

PACS Nos.: 45.20Jj, 11.30Cp, 03.50De
Classical harmonic oscillator approach of a helical-wiggler free-electron laserwith axial guide field
Authors: Rhimi M N , El-Bahi R , Cheikhrouhou A W
Published: April 2011

Electron beam dynamics in a helical-wiggler free-electron laser (FEL) with a uniform axial guide magnetic field are studied using a three-dimensional Hamiltonian approach. The basic feature of the analysis is the definition of a rotational variable, [Formula: see text], that plays the primordial role in lowering to the half the dimension of the quadratic Hamiltonian as a system of two uncoupled oscillators with definite frequencies and amplitudes. It is through applying this variable in the vicinity of a fixed point that the Heisenberg picture of the dynamics of the particles comes to light, leading thus to the association of the steady-state ideal helical trajectories with arbitrary trajectories. The approach recognized the usual two constants of motion, one being the total energy while the other is the canonical axial angular momentum, Pz'. If the value of the latter is such that a fixed point exists, the Hamiltonian is expanded about the fixed point up to second order. The so-obtained oscillator characteristic frequencies allowed one to study the different modes of propagation and to identify, and then avoid the problematic operating conditions of the FEL concerned. On the other hand, the amplitudes of the oscillations, which do depend on the frequencies, are fortunately found to be constants of motion and then controlled by the boundary conditions (initial conditions).

PACS Nos.: 52.40-w, 52.60+h, 42.55.Tb, 52.75Ms
Radiation effect on heat transfer over a stretching surface
Authors: Elbashbeshy E MA
Published: April 2011

We determine the effect of radiation on the forced convection flow of an optically dense incompressible fluid along a heated horizontal stretching surface. The boundary-layer equations are transformed to ordinary differential equations containing a radiation parameter R*, velocity exponent parameter M, Prandtl number P r, and surface temperature parameter θ ω. The effect of these parameters are studied. Graphical results for the velocity and temperature are presented and discussed. PACS Nos.: 44.40+a, 47.27-i
Observation of the 4f 3dσ transition of the ArH molecule
Authors: Nowlan C R , Tokaryk D W , Watson J KG
Published: April 2011

The emission spectrum of ArH contains a band near 10 110 cm1 that appears to be the analogue of the 3dσ  4p, v = 0  0, band of ArD, observed and analysed near 10 230 cm1. However, previous attempts to assign the rotational structure of this band of ArH were unsuccessful. Here we observe and analyse the 4f  3dσ band of ArH near 4400 cm1, and are then able to calculate the rotational structure of the 3dσ  4p transition entirely from known data. The observed band is similar but not identical to the calculated band. We speculate that the observed spectrum is a v  v sequence band of 3dσ  4p, where the v [Formula: see text] 0 upper state is populated through some mechanism peculiar to this isotopomer. PACS No.: 33.20
l-Type doubling: Herzberg versus Nielsen
Authors: Watson J KG
Published: April 2011

In 1942 Gerhard Herzberg demonstrated the existence of l-type doubling in a number of bending fundamental levels of linear molecules. He attributed the doubling partly to asymmetric-top effects and partly to Coriolis interactions with the stretching modes, but Harald Nielsen and Wave Shaffer claimed that it is a purely Coriolis effect. The dispute, which was due mainly to errors in theoretical calculations, lasted for several years. This paper presents a summary of the controversy, based on published papers and letters exchanged between the main participants. PACS No.: 33.10
Quantum defect theory of dipole-mixed Rydberg states in CaF
Authors: Jungen Ch. , Roche A L
Published: April 2011

491 rovibronic levels of electronically highly excited CaF have been analyzed using multichannel quantum defect theory (MQDT). These levels, observed in the experiments described in the preceding paper, correspond to effective principal quantum numbers ν [Formula: see text] 1218, partial wave components l = 03, and vibrationrotation quantum numbers ν = 1 and N = 014. A set of nondiagonal quantum defect matrices has been extracted from the experimental data by means of a global least-squares-fitting procedure, and is found to agree reasonably well with the theoretical quantum defect matrices calculated previously by Arif et al. J. Chem. Phys. 106, 4102 (1997) where the variational R-matrix method was used. The MQDT analysis accounts for rotationalelectronic nonadiabatic decoupling of the Rydberg electron from the rotating dipolar core as well as for strong l-mixing induced by the latter. The quantum defects determined for l = 3 yield approximate values for the core dipole and quadrupole moments. PACS Nos.: 33.10Lb, 34.50Gb, 34.60+z
Intermolecular interactions between tropolone and fluoromethanes
Authors: MacKenzie V J , Steer R P
Published: April 2011

Van der Waals complexes of tropolone (TRN) with CF4, CFH3, CF2H2, and CF3H have been synthesized by expanding mixtures of TRN and the fluorinated methane (FM) in a supersonic free-jet and have been examined using laser induced fluorescence excitation spectroscopy. The sign and magnitude of the microscopic solvent shifts and the magnitude of the tunneling doublet splittings of the origin bands of each distinct complex have been determined from the LIFE spectra. These data, together with both empirical and ab initio calculations of the potential energy surfaces of the 1:1 complexes, have been used to assign the structures of the complexes and determine their approximate binding energies. Expansion of TRN with CF4 produces one identifiable 1:1 complex in which the solvent is primarily dispersively bound and lies above the TRN ring in a symmetric three-legged stool conformation. Expansion of TRN with CFH3 produces two 1:1 complexes, both primarily dispersively bound, in which the solvent molecule lies above the seven-membered ring of TRN in a three-legged stool conformation but which differ in the conformational orientation of the CFH3 species on the TRN surface. Expansion of TRN with CF2H2 produces one 1:1 complex in which the solvent molecule lies above the plane of the TRN ring, but is considerably displaced from its centre of mass and in which binding is primarily electrostatic rather than dispersive. All three partially fluorinated methane molecules produce 1:1 complexes with TRN in which the solvent is bound in the TRN plane by intermolecular hygrogen-bonding. Such structures partially disrupt the intramolecular hydrogen bond of the chromophore and consequently exhibit LIFE spectra characterized by intense, strongly blue-shifted origin bands in which the proton tunneling doublets are unresolvable because of a large decrease in the intramolecular proton tunneling rate. The existence of good correlations between the solute-solvent binding energy and the microscopic solvent shift and between the binding energy and the proton affinities of the solvent for the entire group of hydrogen-bonding solvents, including the partially fluorinated methanes, suggests that CF ... HO and FCH ... O = C interactions result in weak hydrogen bonds which are not qualitatively different from those of more traditional hydrogen-bonding species. PACS No.: 33.20L, 35.20B