bluuebunny/crossref_metadata_2025 huggingface dataset:
Sporulation Phenotype of aBacillus subtilisMutant Expressing an Unprocessable but Active σETranscription Factor
Authors: McBride Shonna , Haldenwang W. G.
Published: March 2004

σE, a sporulation-specific sigma factor ofBacillus subtilis, is formed from an inactive precursor (pro-σE) by a developmentally regulated processing reaction that removes 27 amino acids from the proprotein's amino terminus. AsigEvariant (sigE335) lacking 15 amino acids of the prosequence is not processed into mature σEbut is active without processing. In the present work, we investigated the sporulation defect insigE335-expressingB. subtilis, asking whether it is the bypass of proprotein processing or a residual inhibition of σEactivity that is responsible. Fluorescence microscopy demonstrated thatsigE335-expressingB. subtilisprogresses further into sporulation (stage III) than do strains lacking σEactivity (stage II). Consistent with its stage III phenotype, and a defect in σEactivity rather than its timing, thesigE335allele did not disturb early sporulation gene expression but did inhibit the expression of late sporulation genes (gerEandsspE). The Spo−phenotype ofsigE335was found to be recessive to wild-typesigE. In vivo assays of σEactivity insigE,sigE335, and merodiploid strains indicate that the residual prosequence on σE335, still impairs its activity to function as a transcription factor. The data suggest that the 11-amino-acid extension on σE335allows it to bind RNA polymerase and direct the resulting holoenzyme to σE-dependent promoters but reduces the enzyme's ability to initiate transcription initiation and/or exit from the promoter.
Hydrogen Peroxide Production in
Streptococcus pyogenes
: Involvement of Lactate Oxidase and Coupling with Aerobic Utilization of Lactate
Authors: Seki Masanori , Iida Ken-ichiro , Saito Mitsumasa , Nakayama Hiroaki , Yoshida Shin-ichi
Published: March 2004

Streptococcus pyogenes
strains can be divided into two classes, one capable and the other incapable of producing H
2
O
2
(M. Saito, S. Ohga, M. Endoh, H. Nakayama, Y. Mizunoe, T. Hara, and S. Yoshida, Microbiology
147:
2469-2477, 2001). In the present study, this dichotomy was shown to parallel the presence or absence of H
2
O
2
-producing lactate oxidase activity in permeabilized cells. Both lactate oxidase activity and H
2
O
2
production under aerobic conditions were detectable only after glucose in the medium was exhausted. Thus, the glucose-repressible lactate oxidase is likely responsible for H
2
O
2
production in
S. pyogenes
. Of the other two potential H
2
O
2
-producing enzymes of this bacterium, NADH and α-glycerophosphate oxidase, only the former exhibited low but significant activity in either class of strains. This activity was independent of the growth phase, suggesting that the protein may serve in vivo as a subunit of the H
2
O
2
-scavenging enzyme NAD(P)H-linked alkylhydroperoxide reductase. The activity of lactate oxidase was associated with the membrane while that of NADH oxidase was in the soluble fraction, findings consistent with their respective physiological roles, i.e., the production and scavenging of H
2
O
2
. Analyses of fermentation end products revealed that the concentration of lactate initially increased with time and decreased on glucose exhaustion, while that of acetate increased during the culture. These results suggest that the lactate oxidase activity of H
2
O
2
-producing cells oxidizes lactate to pyruvate, which is in turn converted to acetate. This latter process proceeds presumably via acetyl coenzyme A and acetyl phosphate with formation of extra ATP.
A DNA Adenine Methyltransferase of
Escherichia coli
That Is Cell Cycle Regulated and Essential for Viability
Authors: Kossykh Valeri G. , Lloyd R. Stephen
Published: March 2004

DNA sequence analysis revealed that the putative
yhdJ
DNA methyltransferase gene of
Escherichia coli
is 55% identical to the
Nostoc
sp. strain PCC7120 gene encoding DNA methyltransferase AvaIII, which methylates adenine in the recognition sequence, ATGCAT. The
yhdJ
gene was cloned, and the enzyme was overexpressed and purified. Methylation and restriction analysis showed that the DNA methyltransferase methylates the first adenine in the sequence ATGCAT. This DNA methylation was found to be regulated during the cell cycle, and the DNA adenine methyltransferase was designated M.EcoKCcrM (for “cell cycle-regulated methyltransferase”). The CcrM DNA adenine methyltransferase is required for viability in
E. coli
, as a strain lacking a functional genomic copy of
ccrM
can be isolated only in the presence of an additional copy of
ccrM
supplied in
trans
. The cells of such a knockout strain stopped growing when expression of the inducible plasmid
ccrM
gene was shut off. Overexpression of M.EcoKCcrM slowed bacterial growth, and the ATGCAT sites became fully methylated throughout the cell cycle; a high proportion of cells with an anomalous size distribution and DNA content was found in this population. Thus, the temporal control of this methyltransferase may contribute to accurate cell cycle control of cell division and cellular morphology. Homologs of M.EcoKCcrM are present in other bacteria belonging to the gamma subdivision of the class
Proteobacteria
, suggesting that methylation at ATGCAT sites may have similar functions in other members of this group.
Effect of
d
-Lactate on the Physiological Activity of the ArcB Sensor Kinase in
Escherichia coli
Authors: Rodriguez Claudia , Kwon Ohsuk , Georgellis Dimitris
Published: March 2004

The Arc two-component system, comprising the ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous genes in response to the respiratory growth conditions. Under anoxic growth conditions ArcB autophosphorylates and transphosphorylates ArcA, which in turn represses or activates its target operons. The anaerobic metabolite
d
-lactate has been shown to stimulate the in vitro autophosphorylating activity of ArcB. In this study, the in vivo effect of
d
-lactate on the kinase activity of ArcB was assessed. The results demonstrate that
d
-lactate does not act as a direct signal for activation of ArcB, as previously proposed, but acts as a physiologically significant effector that amplifies ArcB kinase activity.
Protective Role for H-NS Protein in IS
1
Transposition
Authors: Rouquette Claudine , Serre Marie-Claude , Lane David
Published: March 2004

The transposase (InsAB′) of the insertion element IS
1
can create breaks in DNA that lead to induction of the SOS response. We have used the SOS response to InsAB′ to screen for host mutations that affect InsAB′ function and thus point to host functions that contribute to the IS
1
transposition mechanism. Mutations in the
hns
gene, which codes for a DNA binding protein with wide-ranging effects on gene expression, abolish the InsAB′-induced SOS response. They also reduce transposition, whether by simple insertion or cointegrate formation, at least 100-fold compared with the frequency seen in

hns
+

cells. Examination of protein profiles revealed that in an
hns
-null mutant, InsAB′ is undetectable under conditions where it constitutes the most abundant protein in

hns
+

cells. Likewise, brief labeling of the
hns
cells with [
35
S]methionine revealed very small amounts of InsAB′, and this was undetectable after a short chase. Transcription from the promoters used to express
insAB
′ was essentially unaltered in
hns
cells, as was the level of
insAB
′ mRNA. A mutation in
lon
, but not in
ftsH
or
clpP
, restored InsAB′ synthesis in the
hns
strain, and a mutation in
ssrA
partially restored it, implying that the absence of H-NS leads to a problem in completing translation of
insAB
′ mRNA and/or degradation of nascent InsAB′ protein.
Restricted Distribution of the Butyrate Kinase Pathway among Butyrate-Producing Bacteria from the Human Colon
Authors: Louis Petra , Duncan Sylvia H. , McCrae Sheila I. , Millar Jacqueline , Jackson Michelle S. , Flint Harry J.
Published: March 2004

The final steps in butyrate synthesis by anaerobic bacteria can occur via butyrate kinase and phosphotransbutyrylase or via butyryl-coenzyme A (CoA):acetate CoA-transferase. Degenerate PCR and enzymatic assays were used to assess the presence of butyrate kinase among 38 anaerobic butyrate-producing bacterial isolates from human feces that represent three different clostridial clusters (IV, XIVa, and XVI). Only four strains were found to possess detectable butyrate kinase activity. These were also the only strains to give PCR products (verifiable by sequencing) with degenerate primer pairs designed within the butyrate kinase gene or between the linked butyrate kinase/phosphotransbutyrylase genes. Further analysis of the butyrate kinase/phosphotransbutyrylase genes of one isolate, L2-50, revealed similar organization to that described previously from different groups of clostridia, along with differences in flanking sequences and phylogenetic relationships. Butyryl-CoA:acetate CoA-transferase activity was detected in all 38 strains examined, suggesting that it, rather than butyrate kinase, provides the dominant route for butyrate formation in the human colonic ecosystem that contains a constantly high concentration of acetate.
A Novel Gene (
narM
) Required for Expression of Nitrate Reductase Activity in the Cyanobacterium
Synechococcus elongatus
Strain PCC7942
Authors: Maeda Shin-ichi , Omata Tatsuo
Published: March 2004

A new class of mutants deficient in nitrate assimilation was obtained from the cyanobacterium
Synechococcus elongatus
strain PCC7942 by means of random insertional mutagenesis. A 0.5-kb genomic region had been replaced by a kanamycin resistance gene cassette in the mutant, resulting in inactivation of two genes, one of which was homologous to the recently characterized
cnaT
gene of
Anabaena
sp. strain PCC7120 (J. E. Frías, A. Herrero, and E. Flores, J. Bacteriol.
185:
5037-5044, 2003). While insertional mutation of the
cnaT
homolog did not affect expression of the nitrate assimilation operon or the activity of the nitrate assimilation enzymes in
S. elongatus
, inactivation of the other gene, designated
narM
, resulted in specific loss of the cellular nitrate reductase activity. The deduced NarM protein is a hydrophilic protein consisting of 161 amino acids.
narM
was expressed constitutively at a low level. The
narM
gene has its homolog only in the cyanobacterial strains that are capable of nitrate assimilation. In most of the cyanobacterial strains,
narM
is located downstream of
narB
, the structural gene of the cyanobacterial nitrate reductase, suggesting the functional link between the two genes. NarM is clearly not the structural component of the cyanobacterial nitrate reductase. The
narM
insertional mutant normally expressed
narB
, indicating that
narM
is not the transcriptional regulator of the structural gene of nitrate reductase. These results suggested that
narM
is required for either synthesis of the prosthetic group of nitrate reductase or assembly of the prosthetic groups to the NarB polypeptide to form functional nitrate reductase in cyanobacteria.
Sequence Polymorphism in the Glycosylation Island and Flagellins of
Pseudomonas aeruginosa
Authors: Arora Shiwani K. , Wolfgang Matthew C. , Lory Stephen , Ramphal Reuben
Published: March 2004

A genomic island consisting of 14 open reading frames,
orfA
to
orfN
was previously identified in
Pseudomonas aeruginosa
strain PAK and shown to be essential for glycosylation of flagellin. DNA microarray hybridization analysis of a number of
P. aeruginosa
strains from diverse origins showed that this island is polymorphic. PCR and sequence analysis confirmed that many
P. aeruginosa
strains carry an abbreviated version of the island (short island) in which
orfD
, -
E
and -
H
are polymorphic and
orfI
, -
J
, -
K
, -
L
, and -
M
are absent. To ascertain whether there was a relationship between the inheritance of the short island and specific flagellin sequence variants, complete or partial nucleotide sequences of flagellin genes from 24 a-type
P. aeruginosa
strains were determined. Two distinct flagellin subtypes, designated A1 and A2, were apparent. Strains with the complete 14-gene island (long island) were almost exclusively of the A1 type, whereas strains carrying the short island were associated with both A1- and A2-type flagellins. These findings indicate that
P. aeruginosa
possesses a relatively low number of distinct flagellin types and probably has the capacity to further diversify this antigenic surface protein by glycosylation.
Cell Death in
Escherichia coli dnaE
(Ts) Mutants Incubated at a Nonpermissive Temperature Is Prevented by Mutation in the
cydA
Gene
Authors: Strauss Bernard , Kelly Kemba , Dincman Toros , Ekiert Damian , Biesieda Theresa , Song Richard
Published: March 2004

Cells of the
Escherichia coli dnaE
(Ts)
dnaE74
and
dnaE486
mutants die after 4 h of incubation at 40°C in Luria-Bertani medium. Cell death is preceded by elongation, is inhibited by chloramphenicol, tetracycline, or rifampin, and is dependent on cell density. Cells survive at 40°C when they are incubated at a high population density or at a low density in conditioned medium, but they die when the medium is supplemented with glucose and amino acids. Deletion of
recA
or
sulA
has no effect. We isolated suppressors which survived for long periods at 40°C but did not form colonies. The suppressors protected against hydroxyurea-induced killing. Sequence and complementation analysis indicated that suppression was due to mutation in the
cydA
gene. The DNA content of
dnaE
mutants increased about eightfold in 4 h at 40°C, as did the DNA content of the suppressed strains. The amount of plasmid pBR322 in a
dnaE74
strain increased about fourfold, as measured on gels, and the electrophoretic pattern appeared to be normal even though the viability of the parent cells decreased 2 logs. Transformation activity also increased. 4′,6′-Diamidino-2-phenylindole staining demonstrated that there were nucleoids distributed throughout the
dnaE
filaments formed at 40°C, indicating that there was segregation of the newly formed DNA. We concluded that the DNA synthesized was physiologically competent, particularly since the number of viable cells of the suppressed strain increased during the first few hours of incubation. These observations support the view that
E. coli
senses the rate of DNA synthesis and inhibits septation when the rate of DNA synthesis falls below a critical level relative to the level of RNA and protein synthesis.
Comparative Genomics of Two
Leptospira interrogans
Serovars Reveals Novel Insights into Physiology and Pathogenesis
Authors: Nascimento A. L. T. O. , Ko A. I. , Martins E. A. L. , Monteiro-Vitorello C. B. , Ho P. L. , Haake D. A. , Verjovski-Almeida S. , Hartskeerl R. A. , Marques M. V. , Oliveira M. C. , Menck C. F. M. , Leite L. C. C. , Carrer H. , Coutinho L. L. , Degrave W. M. , Dellagostin O. A. , El-Dorry H. , Ferro E. S. , Ferro M. I. T. , Furlan L. R. , Gamberini M. , Giglioti E. A. , Góes-Neto A. , Goldman G. H. , Goldman M. H. S. , Harakava R. , Jerônimo S. M. B , Junqueira-de-Azevedo I. L. M. , Kimura E. T. , Kuramae E. E. , Lemos E. G. M. , Lemos M. V. F. , Marino C. L. , Nunes L. R. , de Oliveira R. C. , Pereira G. G. , Reis M. S. , Schriefer A. , Siqueira W. J. , Sommer P. , Tsai S. M. , Simpson A. J. G. , Ferro J. A. , Camargo L. E. A. , Kitajima J. P. , Setubal J. C. , Van Sluys M. A.
Published: March 2004

Leptospira
species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in accidental hosts, including humans. Complete genome sequencing of
Leptospira interrogans
serovar Copenhageni and comparative analysis with the available
Leptospira interrogans
serovar Lai genome reveal that despite overall genetic similarity there are significant structural differences, including a large chromosomal inversion and extensive variation in the number and distribution of insertion sequence elements. Genome sequence analysis elucidates many of the novel aspects of leptospiral physiology relating to energy metabolism, oxygen tolerance, two-component signal transduction systems, and mechanisms of pathogenesis. A broad array of transcriptional regulation proteins and two new families of afimbrial adhesins which contribute to host tissue colonization in the early steps of infection were identified. Differences in genes involved in the biosynthesis of lipopolysaccharide O side chains between the Copenhageni and Lai serovars were identified, offering an important starting point for the elucidation of the organism's complex polysaccharide surface antigens. Differences in adhesins and in lipopolysaccharide might be associated with the adaptation of serovars Copenhageni and Lai to different animal hosts. Hundreds of genes encoding surface-exposed lipoproteins and transmembrane outer membrane proteins were identified as candidates for development of vaccines for the prevention of leptospirosis.
Reconstruction of the Central Carbohydrate Metabolism of
Thermoproteus tenax
by Use of Genomic and Biochemical Data
Authors: Siebers Bettina , Tjaden Britta , Michalke Klaus , Dörr Christine , Ahmed Hatim , Zaparty Melanie , Gordon Paul , Sensen Christoph W. , Zibat Arne , Klenk Hans-Peter , Schuster Stephan C. , Hensel Reinhard
Published: March 2004

The hyperthermophilic, facultatively heterotrophic crenarchaeum
Thermoproteus tenax
was analyzed using a low-coverage shotgun-sequencing approach. A total of 1.81 Mbp (representing 98.5% of the total genome), with an average gap size of 100 bp and 5.3-fold coverage, are reported, giving insights into the genome of
T. tenax
. Genome analysis and biochemical studies enabled us to reconstruct its central carbohydrate metabolism.
T. tenax
uses a variant of the reversible Embden-Meyerhof-Parnas (EMP) pathway and two different variants of the Entner-Doudoroff (ED) pathway (a nonphosphorylative variant and a semiphosphorylative variant) for carbohydrate catabolism. For the EMP pathway some new, unexpected enzymes were identified. The semiphosphorylative ED pathway, hitherto supposed to be active only in halophiles, is found in
T. tenax
. No evidence for a functional pentose phosphate pathway, which is essential for the generation of pentoses and NADPH for anabolic purposes in bacteria and eucarya, is found in
T. tenax
. Most genes involved in the reversible citric acid cycle were identified, suggesting the presence of a functional oxidative cycle under heterotrophic growth conditions and a reductive cycle for CO
2
fixation under autotrophic growth conditions. Almost all genes necessary for glycogen and trehalose metabolism were identified in the
T. tenax
genome.
Bacillus anthracisandBacillus cereusPcrA Helicases Can Support DNA Unwinding and In Vitro Rolling-Circle Replication of Plasmid pT181 ofStaphylococcus aureus
Authors: Anand Syam P. , Mitra Poulami , Naqvi Asma , Khan Saleem A.
Published: March 2004

Replication of rolling-circle replicating (RCR) plasmids in gram-positive bacteria requires the unwinding of initiator protein-nicked plasmid DNA by the PcrA helicase. In this report, we demonstrate that heterologous PcrA helicases fromBacillus anthracisandBacillus cereusare capable of unwindingStaphylococcus aureusplasmid pT181 from the initiator-generated nick and promoting in vitro replication of the plasmid. These helicases also physically interact with the RepC initiator protein of pT181. The ability of PcrA helicases to unwind noncognate RCR plasmids may contribute to the broad-host-range replication and dissemination of RCR plasmids in gram-positive bacteria.
The PaaX Repressor, a Link between Penicillin G Acylase and the Phenylacetyl-Coenzyme A Catabolon of
Escherichia coli
W
Authors: Galán Beatriz , García José L. , Prieto María A.
Published: March 2004

The
pac
gene, encoding the penicillin G acylase from
Escherichia coli
W, is regulated by the PaaX repressor of the phenylacetate catabolic pathway.
pac
expression depends on the synthesis of phenylacetyl-coenzyme A. PaaX and the cyclic AMP receptor protein (CRP) bind in vitro to the
Ppac
promoter region. A palindromic sequence proposed as the PaaX operator is located upstream of the −35 box overlapping a CRP binding site, an unusual position that suggests a novel regulatory mechanism.
Compartmentalization of Gene Expression during Sporulation of
Bacillus subtilis
Is Compromised in Mutants Blocked at Stage III of Sporulation
Authors: Li Zusheng , Di Donato Francis , Piggot Patrick J.
Published: March 2004

Mutations in the
spoIIIA
and
spoIIIJ
loci disrupt the compartmentalization of gene expression during sporulation of
Bacillus subtilis
. The breakdown in compartmentalization is not the cause of their being blocked in spore formation. Rather, it appears to be a consequence of the engulfed prespore's being unstable.
Distribution and burdens of bioaccumulative contaminants in the Lake Erie food web: A review
Authors: Gewurtz Sarah B , Diamond Miriam L
Published: March 2004

The bioaccumulation of organic contaminants in the Lake Erie food web is reviewed in context of the numerous changes experienced by the system. In the late 1960s, internal lake processes, related to the eutrophic status of the lake, minimized contaminant bioaccumulation despite high contaminant loadings. From the 1970s to 1980s contaminant concentrations decreased at different rates in many species of different trophic levels, coincident with decreased loadings to the lake. Since the early 1980s contaminant concentrations in biota have not changed consistently. Several factors have been proposed to account for these patterns, including reduced nutrient loadings and productivity, and the invasion of several exotic species such as zebra mussels. These factors have altered the food web structure and the internal distribution of contaminants in the lake. Emerging and continuing issues, such as climate change, invasions of additional exotic species, new chemical contaminants of concern, and algal toxins will likely impact contaminant dynamics in the future.Key words: Lake Erie, bioaccumulative contaminants, food web.
Effect of light, salinity, and temperature on seed germination ofLimonium stocksii
Authors: Zia Sabahat , Khan M Ajmal
Published: March 2004

Limonium stocksii (Boiss.) Kuntze (Plumbaginaceae) is a perennial, woody shrub distributed at Hawks Bay, Karachi, Pakistan. Experiments were carried out to investigate seed germination responses of L. stocksii at different salinities (0, 100, 200, 300, 400, and 500 mmol/L NaCl) and under different temperature regimes (10:20, 15:25, 20:30, and 25:35 °C), both in a 12 h dark : 12 h light photoperiod and in complete darkness. The highest percentage of germination (about 100%) was obtained at 0, 100, and 200 mmol/L NaCl at 20:30 °C, and a further increase in salinity resulted in a gradual decrease in germination. Less than 5% of seeds germinated at 500 mmol/L NaCl. Germination under salinity treatment at 15:25 °C was slightly more inhibitory than the optimal temperature regime, whereas under both 10:20 and 25:35 °C temperature regimes, seed germination was substantially reduced and few seeds germinated at concentrations higher than 200 mmol/L NaCl. Germination rate was fastest at 20:30 °C and slowest at 10:20 °C. Relatively low seed germination was obtained in the dark in comparison to seeds germinated in a 12-h photoperiod under saline conditions. Recovery experiments showed that exposure of seeds to various salinity and temperature regimes had little effect on viability of seeds.Key words: germination, light, Limonium stocksii, NaCl, recovery, temperature.
Water relations and yield inAzospirillum-inoculated wheat exposed to drought in the field
Authors: Creus Cecilia M , Sueldo Rolando J , Barassi Carlos A
Published: March 2004

There are scarce data connecting water relations in Azospirillum-inoculated wheat suffering drought during anthesis with the yield and mineral content of grains. Azospirillum brasilense Sp245-inoculated seeds of Triticum aestivum 'Pro INTA Oasis' were sown in nonirrigated and control plots. Water potential, water content, and relative water content were determined on flag leaves. Plant water status was calculated from pressurevolume curves. At maturity, grain yield and its components were determined. P, Ca, Mg, K, Fe, Cu, and Zn were determined in dried grains. Even though the cultivar underwent osmotic adjustment, significantly higher water content, relative water content, water potential, apoplastic water fraction, and lower cell wall modulus of elasticity values were obtained in Azospirillum-inoculated plants suffering drought. Grain yield loss to drought was 26.5% and 14.1% in noninoculated and Azospirillum-inoculated plants, respectively. Grain Mg and K diminished in nonirrigated, noninoculated plots. However, grains harvested from Azospirillum-inoculated plants had significantly higher Mg, K, and Ca than noninoculated plants. Neither drought nor inoculation changed grain P, Cu, Fe, and Zn contents. A better water status and an additional "elastic adjustment" in Azospirillum-inoculated wheat plants could be crucial in promoting higher grain yield and mineral quality at harvest, particularly when drought strikes during anthesis.Key words: Azospirillum, wheat, drought, pressurevolume curves, yield, mineral content.
Morphological and anatomical development in the Vitaceae. VII. Floral development in Rhoicissus digitata with respect to other genera in the family
Authors: Gerrath Jean M , Wilson T , Posluszny Usher
Published: March 2004

This study forms part of our series of investigations on genera in the Vitaceae and is the first developmental study for the genus Rhoicissus. Vegetative and reproductive development of shoot apices of Rhoicissus digitata (L.f.) Gilg et Brandt were examined using epi-illumination light microscopy and scanning electron microscopy. Leaf-opposed tendrils or inflorescences, typical of the shoot architecture in the Vitaceae, were present at every node. Macroscopically, the shoot appears to grow either monopodially or sympodially. At the microscopic level, however, shoot development is sympodial; the shoot apical meristem bifurcates unequally, with the larger portion forming an uncommitted primordium, which will become either an inflorescence or a tendril, and the smaller portion (in the position of the axillary bud) forming the new shoot apical meristem. Floral primordia first initiate three sepals followed by a calyx ring on which the last two sepal primordia form. The five petals are initiated in a whorl followed by the five stamens in a petal-opposed position. There is no evidence of a common petal-stamen primordium in this species. The gy noecium is initiated as a ring primordium. Subsequently, the four ovules are initiated at the base of the two septa that grow out from the inner gynoecial wall. The nectary disc forms as an outgrowth of the gynoecium base. Mature flowers have greenish petals and a red nectariferous disc. Flowers are bisexual, and seed germination is approximately 63%. Unlike previous studies in Vitis and Parthenocissus, Rhoicissus appears to have few putatively derived floral developmental characters, which would support its relatively basal position in current phylogenies for the family.Key words: Vitaceae, morphology, development, shoot architecture, flower.
Within-tree variations in shoot differentiation patterns of 10 tall tree species in a Japanese cool-temperate forest
Authors: Yagi Takanobu
Published: March 2004

The relations of leafstem balance, stem thickness, leaf thickness, and leaf size to stem length of current-year shoots were compared between terminal and lateral shoots in saplings of 10 tall tree species in a Japanese cool-temperate forest. Six monopodial and four substitution sympodial branching species were studied. For both terminal and lateral shoots, the ratios of leaf area / stem length, leaf mass / stem mass, and leaf number / stem length were greater in shorter current-year shoots, implying shoot differentiation such that short current-year shoots specialize in leaf display and long current-year shoots in crown expansion. These ratios were generally greater for terminal shoots than for lateral shoots, especially in the lower range of stem length. This tendency was more conspicuous in the ratio leaf area / stem length than in leaf mass / stem mass and leaf number / stem length, because terminal shoots showed greater stem mass / stem length, leaf area / leaf mass, and leaf area / leaf number ratios than lateral shoots. These terminallateral variations were generally greater in the monopodial species than in sympodial species. These observations are discussed in relation to differences in ecological functions and hydraulic architecture between terminal and lateral shoots, and in relation to apical control and branching patterns (the monopodium and the sympodium).Key words: shoot functions, apical control, short shoots, terminal shoots, monopodial branching, substitution sympodial branching.
Multifaceted approach to determine rice straw phytotoxicity
Authors: Inderjit  , Rawat Dhiraj S , Foy Chester L
Published: March 2004

Unharvested rice (Oryza sativa L.) straw gets incorporated into soil and interferes with the growth of the next season's crop. Water-soluble phenolics leached from straw into soil may suppress the growth of the next crop. A study was carried out to investigate (i) the effect of soil treated with rice straw (ashes of burned and unburned) leachates on seedling growth and foliar protein content of mustard (Brassica napus var. toria L.), (ii) the modification of rice straw phytotoxicity with abiotic soil, activated charcoal, and nitrogen solution, and (iii) any change in soil inorganic ions and phenolics after treatment with rice straw leachate. Maximum inhibition in root growth of mustard was observed when it was grown in soil treated with leachate prepared by using 100 g of unburned (71.1%, expt. 1; 60.2%, expt. 2) and ashes of burned straw (53.4%, expt. 1; 31.5%, expt. 2). Compared with the untreated control, an increase was observed in the total phenolic content of soil treated with straw leachate, prepared by taking 100, 80, 60, 40, and 20 g unburned straw. When soils were treated with leachate prepared by taking 100, 80, and 60 g straw, a lower level of inhibition was observed in abiotic soil compared with biotic soil. An opposite trend was observed when soil was treated with leachate prepared by taking 40 and 20 g straw. The addition of charcoal eliminated the inhibitory effects of rice straw leachate when leachates were prepared using 40 and 20 g straw. Inhibitory effects of soil treated with leachate prepared from 100 g straw on root growth of mustard were not eliminated after the addition of nitrogen solution. The present study showed that rice straw leachate interferes with seedling growth of mustard and that water-soluble phenolics play an important role in mustard seedling growth inhibition.Key words: allelopathy, rice straw, rice, mustard, phenolics.
A comparison of genetic variation and structure in the allopolyploidPlatanthera huronensisand its diploid progenitors,Platanthera aquilonisandPlatanthera dilatata(Orchidaceae)
Authors: Wallace Lisa E
Published: March 2004

Intersimple sequence repeat (ISSR) markers are used to compare population genetic structure among three widely distributed orchids: Platanthera huronensis (Nuttall) Lindl., an allopolyploid, and its diploid progenitors, Platanthera aquilonis Sheviak, and Platanthera dilatata (Pursh.) Lindl. ex Beck. Platanthera huronensis is very similar to P. dilatata in the level of genetic diversity at both the population and species levels. Populations of P. aquilonis are generally significantly less variable than populations of the other two species, but at the species level, P. aquilonis is more variable than P. dilatata or P. huronensis. Analyses of molecular variance indicated that most of the variation occurs within populations for P. dilatata (ΦST= 0.48, where ΦSTis the combined percentage of variation occurring among groups and among populations) and P. huronensis (ΦST= 0.36), and among populations for P. aquilonis (ΦST= 0.69). Populations in disparate regions are not strongly differentiated in P. aquilonis (7% among regions), while in P. dilatata 27% of the variation observed among populations is due to significant regional differences. Platanthera huronensis might be less genetically variable than expected of a widely distributed allopolyploid species due to a limited number of origins, genetic bottlenecks, and low levels of gene flow. Self-pollination via autogamy is a likely cause of the lower level of variation and greater structure observed in P. aquilonis.Key words: genetic structure, ISSR marker, Orchidaceae, Platanthera, allopolyploid.
Cryptic dioecy in Actinidia polygama: a test of the pollinator attraction hypothesis
Authors: Kawagoe Tetsuhiro , Suzuki Nobuhiko
Published: March 2004

Female flowers of some dioecious species are known to develop stamens with sterile pollen, a sexual system known as cryptic dioecy. A convincing hypothesis explaining this phenomenon is that stamens in female flowers attract pollinators and so ensure seed production. However, because this hypothesis has rarely been tested experimentally, we tested it in a cryptically dioecious species, Actinidia polygama (Sieb. et Zucc.) Planch. ex Maxim. Our findings show that pollinators do not show a consistent preference based on the sex of the flowers, and that the removal of stamens from female flowers results in a significant reduction in the frequency of insect visits and fruit production. These results strongly support the pollinator attraction hypothesis in A. polygama. Given the evident role of stamens in female flowers in A. polygama reproduction, we discuss why cryptic dioecy is a rare phenomenon.Key words: Actinidia polygama, cryptic dioecy, pseudopollen, pollinator attraction, unisexual flowers.
Integral transforms, convolution products, and first variations
Authors: Kim Bong Jin , Kim Byoung Soo , Skoug David
Published: March 2004

We establish the various relationships that exist among the integral transform ℱα,βF, the convolution product (F∗G)α, and the first variation δF for a class of functionals defined on K[0, T], the space of complex‐valued continuous functions on [0, T] which vanish at zero.
Extension of α‐labelings of quadratic graphs
Authors: Eshghi Kourosh
Published: March 2004

First, a new proof for the existence of an α‐labeling of the quadratic graph Q(3, 4k) is presented. Then the existence of α‐labelings of special classes of quadratic graphs with some isomorphic components is shown.
Hydrodynamic equations for incompressible inviscid fluid in terms of generalized stream function
Authors: Rylov Yuri A.
Published: March 2004

Hydrodynamic equations for ideal incompressible fluid are written in terms of generalized stream function. Two‐dimensional version of these equations is transformed to the form of one dynamic equation for the stream function. This equation contains arbitrary function which is determined by inflow conditions given on the boundary. To determine unique solution, velocity and vorticity (but not only velocity itself) must be given on the boundary. This unexpected circumstance may be interpreted in the sense that the fluid has more degrees of freedom than it was believed. Besides, the vorticity is a less observable quantity as compared with the velocity. It is shown that the Clebsch potentials are used essentially at the description of vortical flow.
Temporal and spatial opportunities for polygamy in a monogamous seahorse, Hippocampus whitei
Authors: Evans Karl , Sadler Laila , Vincent Amanda , Marsden A. Dale
Published: March 2004

The sex with the higher potential reproductive rate is expected to mate polygamously unless there are temporal or spatial constraints on mate availability. We investigated whether such constraints were evident in a population of the monogamous seahorse Hippocampus whitei (family Syngnathidae). Across the whole study site, breeding was more asynchronous than expected by chance. Our findings are thus compatible with the hypothesis that asynchronous breeding may promote and/or maintain monogamy. Asynchrony per se was unlikely to explain monogamy entirely, however, as temporal opportunities for polygamy remained and the males that were nearest one another had the lowest level of asynchrony. Moreover, each animal's home range overlapped with home ranges of potential mates other than their partner, implying a lack of spatial constraints on polygamy. We suggest that H. whitei mated monogamously because the benefits of polygamy were reduced by (1) only small differences in the potential reproductive rates of males and females and/or (2) a mate familiarity effect that increased reproductive success in successive matings. Further research could investigate relationships between mating pattern and varying intersexual differences in potential reproductive rates across syngnathid species.
Ultrasonic responses of CBA pups to the odour of genetically different mice
Authors: Szentgyörgyi Hajnalka , Kapusta Joanna
Published: March 2004

Mouse pups that are separated from the nest and exposed to cold temperature emit ultrasonic calls. These signals are perceived by conspecifics and play an important communicative role in mother-offspring interaction. Newborn mice are able to modify ultrasonic calls in response to different olfactory cues. Three-day-old CBA-strain mouse pups produced fewer sounds in contact with bedding of adult CBA mice than when exposed to genetically unrelated cues of C57BL and DBA adult animals. The pulses were also significantly shorter in the presence of odour of CBA mice than when exposed to another strain. Newborns emitted the shortest signals when in contact with urine of CBA virgin females, but there were no differences in vocalizations in response to odours from intact, castrated, and testosterone-treated castrated CBA males. These results confirm that CBA pups can distinguish the odour of their genotype. The paper also presents the first evidence that CBA pups discriminate the sex of adult animals and that the chemosignals recognized by pups are secreted with urine but are not testosterone-dependent.
Social dynamics of captive western lowland gorillas living in all-male groups
Authors: Lukas K.E. , Maple T.L. , Stoinski T.S. , Kuhar C.W.
Published: March 2004

Male mammals show considerable variation in their association (e.g. single-male, multi-male, all-male groups) and relationship (e.g. affiliative versus intolerant) patterns. Although a number of primates have been observed to form all-male groups, studies of the social dynamics of these groups are limited. This study examined the social interactions of 25 male western lowland gorillas living in nine captive all-male groups. Over 1,300 hours of data were collected using group scan and all-occurrence sampling methodologies. Groups were cohesive, with males spending approximately one-third of their time within 5 meters of another individual. Although complete linear dominance hierarchies within a group were not observed, dominance relationships between individuals were evident for the majority (66%) of dyads. Social interactions varied as a function of age, with subadults engaging in more affiliative behavior and less non-contact aggression than either blackbacks or silverbacks. Visual/olfactory access to females increased non-contact aggression between males. Such results are similar to those found for all-male groups of mountain gorillas in the wild and demonstrate that all-male groups can be a cohesive social unit in this species. They also raise the questions of why all-male groups have rarely been observed in wild populations and how social, ecological and anthropogenic factors influence male sociality.
Factors mediating inter-group encounters in savannah baboons (Papio cynocephalus ursinus)
Authors: Kitchen Dawn , Seyfarth Robert , Cheney Dorothy
Published: March 2004

Inter-group encounters among baboons range from peaceful to aggressive. During 23 months we observed 110 inter-group interactions involving four groups of chacma baboons in the Okavango Delta, Botswana. Results supported the hypothesis that male behavior functions to prevent extra-group males from gaining access to sexually receptive females. Males were more likely to chase females in their own group when estrous females were present, and their chases targeted estrous females more often than expected. Males also chased members of the opposing group more when estrous females were present. When estrous females were absent, male displays were shorter in duration, involved fewer participants, were less intense, and were more likely to result in peaceful mingling between groups. The alpha male was the individual most actively involved in inter-group chases and displays, but males of all ranks participated, especially when they were in consort with a female. However, males did not cooperate in group defense. While behavior during encounters was affected by the presence of estrous females, the outcome of encounters was affected by location and rival group identity. Groups were more likely to approach and displace opponents in the core of their range and more likely to retreat in the periphery. Correcting for location, we also found some evidence for an inter-group dominance hierarchy based on the relative number of males.
Food stress, fluctuating asymmetry and reproductive performance in the gryllid crickets Gryllus bimaculatus and Gryllodes sigillatus
Authors: Mallard Samantha , Barnard C.J.
Published: March 2004

While associations between sexual selection, developmental stress and fluctuating asymmetry (FA) remain controversial, this does not necessarily undermine the more general hypothesis that FA reflects developmental instability and functional competence. This applies as much to reproductive processes as to any other. If this is the case, however, we should expect FA and measures of performance to covary under conditions of developmental stress. Using an established association between morphometric FA and reproductive performance in the gryllid crickets Gryllus bimaculatus and Gryllodes sigillatus, we looked at the effect of food stress on covariation between FA and measures of performance (vigour of locomotion and interaction, mating speed, sperm transfer, egg production and offspring weight). The results showed a clear effect of food treatment in males and females of both species, with composite measures reflecting greater FA and reduced performance being greatest when crickets were reared on impoverished food. Inspection of independent means suggested FA may have been most influenced by a relaxation of food stress under high quality feeding conditions, while reproductive performance was more susceptible to the reduction in food quality under low quality conditions.
Foraging behaviour of Armadillidium vulgare (Isopoda: Oniscidea) in heterogeneous environments
Authors: Tuck Joanne , Hassall Mark
Published: March 2004

Foraging behaviour of Armadillidium vulgare was observed in laboratory arenas in which the spatial distribution of patches of high quality food (powdered dicotyledonous leaf litter) was varied within a background of low quality food (powdered grass leaf litter). The hypotheses that the foraging behaviour and foraging path of A. vulgare would be influenced by food quality and the patchiness of high quality food resources were tested. More time was spent in high quality food patches than in low quality food backgrounds than expected by chance in all heterogeneity treatments, but an increasingly higher percentage of time was spent in low quality food as the high quality food became more clumped in space. More time was spent searching, but less time was spent feeding in low quality food backgrounds than in high quality food patches in all the treatments. Walking speed was found to be lower in high quality food patches than in low quality food backgrounds and this was not affected by treatment. Turning frequency and turning angle were found to be higher in high quality food patches than in low quality backgrounds. Turning frequency in low quality food backgrounds decreased as the high quality food became more clumped in space, whereas turning angle in high quality food patches significantly increased in the patchy, but then decreased again in the clumped treatment. The effects of varying the spatial heterogeneity of high quality foods on the trade-off between costs of searching and intake benefits for saprophages are discussed in relation to predictions from optimal foraging theory for circumstances when intake rate maximisation is affected by the constraint of limited nutrients.
Break-down of arms race between the red-backed shrike (Lanius collurio) and common cuckoo (Cuculus canorus)
Authors: Moskát Csaba , Lovászi Péter
Published: March 2004

The red-backed shrike Lanius collurio once was parasitised by the common cuckoo Cuculus canorus in low frequency until the late 1960s in Hungary, but no case of parasitism is known from the last three or four decades. The cuckoo most probably abandoned this host species because its arms race had defeated, which may be indicated by the high level egg recognition and rejection ability of shrikes. However, mimicry of the cuckoo eggs in the last known cases of parasitism was significantly lower than between cuckoo eggs and host eggs collected from great reed warbler Acrocephalus arundinaceus nests within the same period. This suggests that red-backed shrikes won the arms race leaving no chance for cuckoos to develop better mimicry for their eggs. We tested these findings with experimentally induced parasitism using two types of real eggs: red-backed shrikes rejected 57.6% of the foreign conspecific eggs, but rejected 93.3% of the real cuckoo eggs transferred form nests of great reed warblers. This high level of rejection against real cuckoo eggs shows that there is no chance for presently occurring cuckoos to reparasitise red-backed shrikes in Hungary. Experimental eggs rejected by shrikes had lower mimicry than the eggs which were accepted, but intraclutch variation did not differ between accepters and rejecters. Hosts' aggression was significantly higher against the stuffed cuckoo than against the control species, the collared dove Streptopelia decaocto, and it was the least against female red-backed shrikes. Red-backed shrikes high aggression against cuckoo dummies also showed a highly developed antiparasite adaptation.
Biopolitics, Fascism, Democracy: Some Reflections on Our Discourse About “Modernity”
Authors: Dickinson Edward Ross
Published: March 2004

In recent years the outlines of a new master narrative of modern German history have begun to emerge in a wide range of publications. This narrative draws heavily on the theoretical and historical works of Michel Foucault and Detlev J. K. Peukert, and on the earlier work of the Frankfurt School, Max Weber, and the French theorists of postmodernism. In it, rationalization and science, and specifically the extended discursive field of “biopolitics” (the whole complex of disciplines and practices addressing issues of health, reproduction, and welfare) play a key role as the marker and most important content of modernization. Increasingly, this model has a function in German historiography similar to that long virtually monopolized by the “Sonderwegthesis”: it serves as a broad theoretical or interpretive framework that can guide the construction of meaning in “smaller” studies, which are legitimated by their function in confirming or countering this broader argument.