bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytological Studies on Pelomyxa carolinensis with Special Reference to the Mitochondria*
Authors: TORCH REUBEN 
Published: May 2007

SUMMARY. The mitochondria of living, unstained Pelomyxa carolinensis are homogeneous, nonrefractile bodies and occur as spheres, short rods, dumbbell forms or elongated rods. All forms are distributed uniformly throughout the cytoplasm, except for characteristic accumulations around the contractile vacuoles and small food vacuoles. Mitochondria were never observed within food vacuoles, nor in intimate contact with large food vacuoles containing recently ingested paramecia.Aqueous solutions (1:200,000) of Janus green B, Janus blue, and Janus red stained the mitochondria. After 12 hours in Janus green B and Janus blue or 24 hours in Janus red, the mitochondrion appears as a differentiated structure with the stain localized in eccentric granules or crescentic areas. Aqueous solutions of Janus black (1:200,000), amethyst violet (1:200,000) and Rhodamine B (1:50,000) stained only food vacuoles within the organisms.Dumbbell forms and elongated rods, often interpreted as division stages, were continuously observed in the living organism. These observations failed to reveal any division process.Sectioned material was prepared from animals fixed in Champy's, Regaud's, Altmann's and Helly's fluids, as well as in a fixative composed of equal parts of 1% (w/v) chromic acid and 2% (w/v) osmium tetroxide. Excellent results were obtained with Champy and chrom‐osmic fixation, while the other fixatives proved to be of little value.
Photomotion in Euglena gracilis* I. Photokinesis II. Phototaxis
Authors: WOLKEN J. J. , SHIN E. 
Published: May 2007

SYNOPSIS. Photokinesis or the non‐directed rate of swimming of Euglena gracilis for various light intensities was studied. The rate of swimming in white light was found to increase with light intensity until it reaches 0.16 mm./sec. at a saturation of 40 ft. candles, and then decreased with increasing light intensities. Polarized light appeared to be more effective (0.18 mm./sec. at 13 ft. candles) than non‐polarized light.The action spectrum for photokinesis showed two peaks, a major one near 465 mμ, and another in the neighborhood of 630 mμ, having the values of 0.18 mm./sec. and 0.16 mm./sec. respectively at an intensity of 4 ft. candles.The action spectrum for phototaxis, or directed orientation, had a peak near 420 mμ and showed a maximum near 490 mμ. Both dark‐grown and dark‐adapted Euglena showed spectral peaks similar to those of the light‐grown cells. For polarized light, the action spectrum had two additional peaks at 468 mμ and 508 mμ. The polarized light effect may indicate more than one light‐absorbing pigment within the “eye spot” or that other pigments within Euglena were absorbing.
A Factual Analysis of Chromosomal Movement in Barbulanympha
Authors: CLEVELAND L. R. 
Published: May 2007

SYNOPSIS. The role of eleven different types of achromatic figures in chromosomal movement of Barbulanympha is analyzed. When only one pole is present, no chromosomes are ever connected with it, and hence they do not move. The chromosomes go through their usual life cycle including pairing, but remain in the parent nucleus, which, of course, does not divide. When two poles are present with only one pole near the nucleus, the poles, which are the distal ends of the elongate centrioles, do not cooperate in the formation of a central spindle and the chromosomal behavior is just as if there were only one pole—no movement. The same is true when more than two poles are present with only one near the nucleus.Unless a central spindle is present, movement of chromosomes never occurs. However, when many central spindles are present, sister chromosomes may separate and move to poles which are not directly connected by a central spindle. In other words, sisters may separate without moving along a central spindle.In binucleate cells with one central spindle the chromosomes of one nucleus move to the poles, but those of the other do not. Movement always occurs in the nucleus that has its nuclear membrane depressed by the central spindle. When two or more central spindles are present, the chromosomes of both nuclei may move to the poles.
Euryhaline Chrysomonads: Nutrition and Toxigenesis in Prymnesium parvum, with Notes on Isochrysis galbana and Monochrysis lutheri
Authors: McLAUGHLIN J. J. A. 
Published: May 2007

SYNOPSIS. The nutritional requirements of 3 isolates of Prymnesium parvum (2 Israeli, 1 Scottish) included vitamin B12 and thiamine. For comparison, 2 other brackish chrysomonads were studied: Monochrysis lutheri isolated by Droop in Scotland and Isochrysis galbana purified by McLaughlin from a culture obtained from the Plymouth laboratory.The isolates of Prymnesium parvum and Isochrysis galbana had a molecular B12 specificity like Ochromonas malhamensis: no response to Factor B, pseudovitamin B12, Factor A or Factor H. M. lutheri, in contrast, responded to pseudovitamin B12, Factor H, and Factor A.Thiamine was essential; 1.0 μg.% allowed full growth of P. parvum. The NaCl concentration for good growth was 0.3–5.0%; growth was possible from 6–12%. Dark growth was not achieved.Ammonia, as suggested from its use in suppressing outbreaks of P. parvum, was sharply inhibitory, less so at high concentrations of NaCl or at acid pH.Nitrate, ammonia, arginine, asparagine, methionine, histidine, alanine, glycine, serine, proline, leucine, isoleucine, tyrosine, aspartic and glutamic acids, acetylurea, and creatine served as nitrogen sources in both acid and alkaline media.The phosphate requirement of P. parvum and M. lutheri and Isochrysis galbana was satisfied by inorganic phosphate, commercial glycerophosphate, yeast adenylic acid, cytidylic acid, monoethyl phosphate, and riboflavin monophosphate.Laboratory cultures in defined media of the isolates of P. parvum were toxigenic to Lebistes and Gambusia. Culture fluids from alkaline media were more toxic than those from acid media, as previously noted in Israel.Culture media suitable for production of large quantities of these organisms were developed.
Early computerized tomography accurately determines the presence or absence of scaphoid and other fractures
Authors: Cruickshank Jaycen , Meakin Alex , Breadmore Ross , Mitchell David , Pincus Steven , Hughes Thomas , Bently Bronwyn , Harris Mark , Vo Austin 
Published: May 2007

AbstractObjective:  To validate the use of early CT in predicting scaphoid fracture and other fractures in patients with suspected scaphoid fracture.Method:  A prospective observational study of adult patients with a diagnosis of clinical scaphoid fracture presenting to a regional ED. Patients were immobilized in a scaphoid plaster and had a CT (wrist and carpals) same or next day. The gold standard used was the diagnosis on Day 10 with clinical examination and X‐rays, with MRI performed in patients with persistent tenderness but normal X‐rays.Results:  Forty‐seven patients completed the study protocol from September 2004 until February 2006. For all fractures, early CT had a 96.8% negative predictive value and 100% positive predictive value (94.4% sensitive, 100% specific). No scaphoid fracture was missed by early CT. One patient had a trapezium fracture on CT, with a coexistent subtle capitate fracture only detected on MRI.Conclusion:  Early CT scans show promise in the diagnosis of scaphoid and other fractures of the wrist and carpals. Further study is warranted to validate early CT in clinical scaphoid fracture as an alternative to other early advanced imaging, or plaster immobilization and 2 week review.
High-Level Production of Beta-Carotene in
Saccharomyces cerevisiae
by Successive Transformation with Carotenogenic Genes from
Xanthophyllomyces dendrorhous
Authors: Verwaal René , Wang Jing , Meijnen Jean-Paul , Visser Hans , Sandmann Gerhard , van den Berg Johan A. , van Ooyen Albert J. J. 
Published: May 2007

ABSTRACT

To determine whether
Saccharomyces cerevisiae
can serve as a host for efficient carotenoid and especially β-carotene production, carotenogenic genes from the carotenoid-producing yeast
Xanthophyllomyces dendrorhous
were introduced and overexpressed in
S. cerevisiae
. Because overexpression of these genes from an episomal expression vector resulted in unstable strains, the genes were integrated into genomic DNA to yield stable, carotenoid-producing
S. cerevisiae
cells. Furthermore, carotenoid production levels were higher in strains containing integrated carotenogenic genes. Overexpression of
crtYB
(which encodes a bifunctional phytoene synthase and lycopene cyclase) and
crtI
(phytoene desaturase) from
X. dendrorhous
was sufficient to enable carotenoid production. Carotenoid production levels were increased by additional overexpression of a homologous geranylgeranyl diphosphate (GGPP) synthase from
S. cerevisiae
that is encoded by
BTS1
. Combined overexpression of
crtE
(heterologous GGPP synthase) from
X. dendrorhous
with
crtYB
and
crtI
and introduction of an additional copy of a truncated 3-hydroxy-3-methylglutaryl-coenzyme A reductase gene (
tHMG1
) into carotenoid-producing cells resulted in a successive increase in carotenoid production levels. The strains mentioned produced high levels of intermediates of the carotenogenic pathway and comparable low levels of the preferred end product β-carotene, as determined by high-performance liquid chromatography. We finally succeeded in constructing an
S. cerevisiae
strain capable of producing high levels of β-carotene, up to 5.9 mg/g (dry weight), which was accomplished by the introduction of an additional copy of
crtI
and
tHMG1
into carotenoid-producing yeast cells. This transformant is promising for further development toward the biotechnological production of β-carotene by
S. cerevisiae
.
Localization of RHO-4 Indicates Differential Regulation of Conidial versus Vegetative Septation in the Filamentous Fungus
Neurospora crassa
Authors: Rasmussen Carolyn G. , Glass N. Louise 
Published: May 2007

ABSTRACT

rho-4
mutants of the filamentous fungus
Neurospora crassa
lack septa and asexual spores (conidia) and grow slowly. In this report, localization of green fluorescent protein-tagged RHO-4 is used to elucidate the differences in factors controlling RHO-4 localization during vegetative growth versus asexual development. RHO-4 forms a ring at incipient vegetative septation sites that constricts with the formation of the septum toward the septal pore; RHO-4 persists around the septal pore after septum completion. During the formation of conidia, RHO-4 localizes to the primary septum but subsequently is relocalized to the cytoplasm after the placement of the secondary septum. Cytoplasmic localization and inactivation of RHO-4 are mediated by a direct physical interaction with RDI-1, a RHO guanosine nucleotide dissociation inhibitor. Inappropriate activation of the cyclic AMP-dependent protein kinase A pathway during vegetative growth causes mislocalization of RHO-4 away from septa to the cytoplasm, a process which was dependent upon RDI-1. An adenylate cyclase
cr-1
mutant partially suppresses the aconidial defect of
rho-4
mutants but only rarely suppresses the vegetative septation defect, indicating that conidial septation is negatively regulated by CR-1. These data highlight the differences in the regulation of septation during conidiation versus vegetative septation in filamentous fungi.
Histidine Auxotrophy in Commensal and Disease-Causing Nontypeable
Haemophilus influenzae
Authors: Juliao Patricia C. , Marrs Carl F. , Xie Jingping , Gilsdorf Janet R. 
Published: May 2007

ABSTRACT

Histidine biosynthesis is one of the best studied metabolic pathways in bacteria. Although this pathway is thought to be highly conserved within and between bacterial species, a previous study identified a genetic region within the histidine operon (
his
) of nontypeable strains of
Haemophilus influenzae
(NTHI) that was more prevalent among otitis media strains than among throat commensal NTHI strains. In the present study, we further characterized this region and showed that genes in the complete his operon (
hisG
, -
D
, -
C
, -
NB
, -
H
, -
A
, -
F
, and -
IE
) are >99% conserved among four fully sequenced NTHI strains, are present in the same location in these four genomes, and are situated in the same gene order. Using PCR and dot blot hybridization, we determined that the
his
operon was significantly more prevalent in otitis media NTHI strains (106/121; 87.7%) than in throat strains (74/137; 54%) (prevalence ratio, 1.62;
P
< 0.0001), suggesting a possible role in middle ear survival and/or acute otitis media. NTHI strains lacking the
his
operon showed attenuated growth in histidine-restricted media, confirming them as
his
-negative auxotrophs. Our results suggest that the ability to make histidine is an important factor in bacterial growth and survival in the middle ear, where nutrients such as histidine may be found in limited amounts. Those isolates lacking the histidine pathway were still able to survive well in the throat, which suggests that histidine is readily available in the throat environment.
Low Concentrations of Bile Salts Induce Stress Responses and Reduce Motility inBacillus cereusATCC 14570
Authors: Kristoffersen Simen M. , Ravnum Solveig , Tourasse Nicolas J. , Økstad Ole Andreas , Kolstø Anne-Brit , Davies William 
Published: May 2007

ABSTRACTTolerance to bile salts was investigated in fortyBacillus cereusstrains, including 17 environmental isolates, 11 dairy isolates, 3 isolates from food poisoning outbreaks, and 9 other clinical isolates. Growth of all strains was observed at low bile salt concentrations, but no growth was observed on LB agar plates containing more than 0.005% bile salts. Preincubation of theB. cereustype strain, ATCC 14579, in low levels of bile salts did not increase tolerance levels.B. cereusATCC 14579 was grown to mid-exponential growth phase and shifted to medium containing bile salts (0.005%). Global expression patterns were determined by hybridization of total cDNA to a 70-mer oligonucleotide microarray. A general stress response and a specific response to bile salts were observed. The general response was similar to that observed in cultures grown in the absence of bile salts but at a higher (twofold) cell density. Up-regulation of several putative multidrug exporters and transcriptional regulators and down-regulation of most motility genes were observed as part of the specific response. Motility experiments in soft agar showed that motility decreased following bile salts exposure, in accordance with the transcriptional data. Genes encoding putative virulence factors were either unaffected or down-regulated.
Two ABC Transporter Operons and the Antimicrobial Resistance Gene
mtrF
Are
pilT
Responsive in
Neisseria gonorrhoeae
Authors: Friedrich Alexandra , Arvidson Cindy G. , Shafer William M. , Lee Eun-Hee , So Magdalene 
Published: May 2007

ABSTRACT

Retraction of type IV pili is mediated by PilT. We show that loss of
pilT
function leads to upregulation of
mtrF
(
m
ultiple
t
ransferable
r
esistance) and two operons encoding putative ABC transporters in
Neisseria gonorrhoeae
MS11. This effect occurs indirectly through the transcriptional regulator FarR, which until now has been shown to regulate only
farAB
.
l
-Glutamine can reverse
pilT
downregulation of the ABC transporter operons and
mtrF
.
Identical, Independent, and Opposing Roles of ppGpp and DksA in
Escherichia coli
Authors: Magnusson Lisa U. , Gummesson Bertil , Joksimović Predrag , Farewell Anne , Nyström Thomas 
Published: May 2007

ABSTRACT

The recent discovery that the protein DksA acts as a coregulator of genes controlled by ppGpp led us to investigate the similarities and differences between the relaxed phenotype of a ppGpp-deficient mutant and the phenotype of a strain lacking DksA. We demonstrate that the absence of DksA and ppGpp has similar effects on many of the observed phenotypes but that DksA and ppGpp also have independent and sometimes opposing roles in the cell. Specifically, we show that overexpression of DksA can compensate for the loss of ppGpp with respect to transcription of the promoters P

uspA

, P

livJ

, and P

rrnBP1

as well as amino acid auxotrophy, cell-cell aggregation, motility, filamentation, and stationary phase morphology, suggesting that DksA can function without ppGpp in regulating gene expression. In addition, ppGpp and DksA have opposing effects on adhesion. In the course of our analysis, we also discovered new features of the relaxed mutant, namely, defects in cell-cell aggregation and motility.
Global Transcriptional Analysis of
Streptococcus mutans
Sugar Transporters Using Microarrays
Authors: Ajdić Dragana , Pham Vi T. T. 
Published: May 2007

ABSTRACT

The transport of carbohydrates by
Streptococcus mutans
is accomplished by the phosphoenolpyruvate-phosphotransferase system (PTS) and ATP-binding cassette (ABC) transporters. To undertake a global transcriptional analysis of all
S. mutans
sugar transporters simultaneously, we used a whole-genome expression microarray. Global transcription profiles of
S. mutans
UA159 were determined for several monosaccharides (glucose, fructose, galactose, and mannose), disaccharides (sucrose, lactose, maltose, and trehalose), a β-glucoside (cellobiose), oligosaccharides (raffinose, stachyose, and maltotriose), and a sugar alcohol (mannitol). The results revealed that PTSs were responsible for transport of monosaccharides, disaccharides, β-glucosides, and sugar alcohol. Six PTSs were transcribed only if a specific sugar was present in the growth medium; thus, they were regulated at the transcriptional level. These included transporters for fructose, lactose, cellobiose, and trehalose and two transporters for mannitol. Three PTSs were repressed under all conditions tested. Interestingly, five PTSs were always highly expressed regardless of the sugar source used, presumably suggesting their availability for immediate uptake of most common dietary sugars (glucose, fructose, maltose, and sucrose). The ABC transporters were found to be specific for oligosaccharides, raffinose, stachyose, and isomaltosaccharides. Compared to the PTSs, the ABC transporters showed higher transcription under several tested conditions, suggesting that they might be transporting multiple substrates.
QseA and GrlR/GrlA Regulation of the Locus of Enterocyte Effacement Genes in EnterohemorrhagicEscherichia coli
Authors: Russell Regan M. , Sharp Faith C. , Rasko David A. , Sperandio Vanessa 
Published: May 2007

ABSTRACTTranscription of the locus of enterocyte effacement (LEE) genes in enterohemorrhagicEscherichia coli(EHEC) is regulated by the LEE-encoded Ler and GrlR/GrlA proteins as well as the non-LEE-encoded regulator QseA. This work demonstrates that GrlR/GrlA activateLEE2transcription in a Ler-independent fashion, whereas transcription ofgrlRAis activated by QseA in both Ler-dependent and -independent manners.
Nitric oxide synthase-derived plasma nitrite predicts exercise capacity
Authors: Rassaf Tienush , Lauer Thomas , Heiss Christian , Balzer Jan , Mangold Sarah , Leyendecker Thorsten , Rottler Jessica , Drexhage Christine , Meyer Christian , Kelm Malte 
Published: May 2007

Background:Nitrite is the main oxidation product of nitric oxide (NO) in plasma. It sensitively reflects changes in endothelial NO synthase (eNOS) activity under fasting conditions and serves as an endocrine NO donor, contributing to the regulation of blood flow through reaction with haemoglobin. As NO is necessary to maintain an adequate vascular response to the increased demands of blood flow, it is believed to be important for vasodilation induced by exercise.Objective:To investigate whether the capacity of the vasculature to produce nitrite is associated with exercise performance.Design:With the use of chemiluminescence detection, nitrite concentrations in 55 healthy subjects (mean (SEM) age 40 (2) years; 22 men) were studied before and after an exercise test, and endothelial function was determined by measuring flow-mediated dilation of the brachial artery using high-resolution ultrasound. In a subset of subjects, the NOS inhibitor,NG-monomethyl-l-arginine, was applied to elucidate the effect of eNOS on changes in nitrite.Results:Exercise significantly (p<0.001) increased plasma nitrite from 97 (6) to 125 (8) nM. The relative increase in plasma nitrite was related to flow-mediated dilation (6.1 (0.3)%; r = 0.36; p = 0.01).NG-Monomethyl-l-arginine blocked increases in nitrite. Post-exercise nitrite concentration correlated with exercise performance, as determined by maximally reached stress power (r = 0.37; p<0.007), and inversely with age. Multivariate analysis showed that both age and post-exercise nitrite concentration were independent predictors of stress endurance and power.Conclusion:The results suggest a role for plasma nitrite in the adaptation of haemodynamics during exercise. An impaired increase in plasma nitrite may limit exercise capacity.
Interleukin-6–dependent survival of multiple myeloma cells involves the Stat3-mediated induction of microRNA-21 through a highly conserved enhancer
Authors: Löffler Dennis , Brocke-Heidrich Katja , Pfeifer Gabriele , Stocsits Claudia , Hackermüller Jörg , Kretzschmar Antje K. , Burger Renate , Gramatzki Martin , Blumert Conny , Bauer Kay , Cvijic Helena , Ullmann A. Kerstin , Stadler Peter F. , Horn Friedemann 
Published: May 2007

Abstract
Signal transducer and activator of transcription 3 (Stat3) is implicated in the pathogenesis of many malignancies and essential for IL-6–dependent survival and growth of multiple myeloma cells. Here, we demonstrate that the gene encoding oncogenic microRNA-21 (miR-21) is controlled by an upstream enhancer containing 2 Stat3 binding sites strictly conserved since the first observed evolutionary appearance of miR-21 and Stat3. MiR-21 induction by IL-6 was strictly Stat3 dependent. Ectopically raising miR-21 expression in myeloma cells in the absence of IL-6 significantly reduced their apoptosis levels. These data provide strong evidence that miR-21 induction contributes to the oncogenic potential of Stat3.