bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Identification of a Calcium-Inhibited Catalytic Subunit of Casein Kinase Type 2 from
Paramecium tetraurelia
Authors: Vetter Daniel , Kissmehl Roland , Treptau Tilman , Hauser Karin , Kellermann Josef , Plattner Helmut 
Published: December 2003

ABSTRACT

We have previously described the occurrence in
Paramecium
of a casein kinase (CK) activity (EC 2.7.1.37) with some unusual properties, including inhibition by Ca
2+
(R. Kissmehl, T. Treptau, K. Hauser, and H. Plattner, FEBS Lett. 402:227-235, 1995). We now have cloned four genes,
PtCK2α1
to
PtCK2α4
, all of which encode the catalytic α subunit of type 2 CK (CK2) with calculated molecular masses ranging from 38.9 to 39.4 kDa and pI values ranging from 8.8 to 9.0. They can be classified into two groups, which differ from each other by 28% on the nucleotide level and by 18% on the derived amino acid level. One of them,
PtCK2α3
, has been expressed in
Escherichia coli
and characterized in vitro. As we also have observed with the isolated CK, the recombinant protein preferentially phosphorylates casein but also phosphorylates some
Paramecium
-specific substrates, including the exocytosis-sensitive phosphoprotein pp63/parafusin. Characteristically, Ca
2+
inhibits the phosphorylation at elevated concentrations occurring during stimulation of a cell. Reconstitution with a recombinant form of the regulatory subunit from
Xenopus laevis
, XlCK2β, confirms Ca
2+
sensitivity also under conditions of autophosphorylation. This is unusual for CK2 but correlates with the presence of two EF-hand calcium-binding motifs, one of which is located in the N-terminal segment essential for constitutive activity, as well as with an aberrant composition of normally basic domains recognizing acidic substrate domains. Immunogold localization reveals a considerable enrichment in the outermost cell cortex layers, excluding cilia. We discuss a potential role of this Ca
2+
-inhibited PtCK2α species in a late step of signal transduction.
Sla1, aSchizosaccharomyces pombeHomolog of the Human La Protein, Induces Ectopic Meiosis when Its C Terminus Is Truncated
Authors: Tanabe Kaori , Ito Noriko , Wakuri Tomomi , Ozoe Fumiyo , Umeda Makoto , Katayama Satoshi , Tanaka Katsunori , Matsuda Hideyuki , Kawamukai Makoto 
Published: December 2003

ABSTRACTSla1 is aSchizosaccharomyces pombehomolog of the human La protein. La proteins are known to be RNA-binding proteins that bear conserved RNA recognition motifs (La and RRMs), but their biological functions still have not been fully resolved. In this study, we show that theS. pombeLa homolog (Sla1) is involved in regulating sexual development. Sla1 truncated in the C terminus (Sla1ΔC) induced ectopic sporulation in theras1Δ strain and several other sporulation-deficient mutants. The C terminus contains a nuclear localization signal. While full-length Sla1 localizes in the nucleus, Sla1ΔC is found throughout the cell, suggesting the cytoplasmic localization of Sla1ΔC is involved in its sporulation-inducing activity. Further deletion analysis of Sla1 indicated that a small region (35 amino acids) that includes a portion of RRM2 is sufficient to induce sporulation. The La motif (RRM1) is not involved in this activity. Strikingly, Sla1ΔC induced haploid meiosis in a heterothallic strain, similar to thepat1-114ormei2-SATAmutation. Sla1ΔC induced sporulation in amei3disruptant but not in amei2disruptant, indicating that Sla1ΔC requires Mei2 to induce haploid meiosis. Deletion of the chromosomalsla1gene lowered the temperature sensitivity of thepat1-114mutant. Two-hybrid analysis indicated that Pat1 interacts with Sla1ΔC but not full-length Sla1. Thus, Sla1ΔC may block Pat1 activity. This block would remove the inhibition on Mei2, which would then drive the cell into haploid meiosis. Finally, Sla1 was degraded prior to the start of meiosis when we monitored Sla1 in cells in which meiosis was synchronously induced. The ability of truncated Sla1 to induce ectopic meiosis represents a very novel function that has hitherto not been suspected for the La family of proteins.
Dictyostelium discoideum
Developmentally Regulated Genes Whose Expression Is Dependent on MADS Box Transcription Factor SrfA
Authors: Escalante Ricardo , Moreno Nicolas , Sastre Leandro 
Published: December 2003

ABSTRACT

The MADS box transcription factor SrfA is required for spore differentiation in
Dictyostelium discoideum. srfA
null strains form rounded spores that do not resist adverse environmental conditions. Five genes whose expression is dependent on SrfA have been isolated by differential hybridization. One of these genes,
sigC
, is identical to
phg1b
, previously characterized in mutants with altered adhesive properties and found to encode a nine-transmembrane-domain protein. This gene is transcribed into two mRNAs as the result of alternative splicing of two internal exons. The slower-migrating mRNA codes for a shorter protein that lacks the first transmembrane fragment and is not expressed in
srfA
null strains. The other four genes (
sigA
,
sigB
,
sigD
, and
45D
) are expressed only during late developmental stages. In situ hybridization experiments showed that expression of
sigA
,
sigB
, and
sigD
is restricted to the sorus of developing structures.
sigA
codes for a homologue of malate dehydrogenase that converts pyruvate to malate to replenish the tricarboxylic acid cycle.
sigB
encodes a protein with significant similarity to the GP63 metalloproteinase of
Leishmania
, leishmanolysin. The sequence of SigD is highly similar to that of several spore coat proteins of
D. discoideum
, and it may play a role in that structure. The gene
45D
codes for an RNA-binding protein homologue whose expression is also dependent on the GATA transcription factor stalky (StkA). The expression of
sigB
is also dependent on both SrfA and StkA. The expression of
45D
, but not of
sigA
,
sigB
,
sigC
, and
sigD
, can be induced in
srfA
null cells by constitutive protein kinase A activation. Strains in which either
sigA
,
sigB
, or
sigD
is disrupted were isolated and found to form spores that are not detectably different from those of wild-type strains.
Cryptococcus neoformans
Gene Expression during Experimental Cryptococcal Meningitis
Authors: Steen B. R. , Zuyderduyn S. , Toffaletti D. L. , Marra M. , Jones S. J. M. , Perfect J. R. , Kronstad J. 
Published: December 2003

ABSTRACT

Cryptococcus neoformans
, an encapsulated basidiomycete fungus of medical importance, is capable of crossing the blood-brain barrier and causing meningitis in both immunocompetent and immunocompromised individuals. To gain insight into the adaptation of the fungus to the host central nervous system (CNS), serial analysis of gene expression (SAGE) was used to characterize the gene expression profile of
C. neoformans
cells recovered from the CNS of infected rabbits. A SAGE library was constructed, and 49,048 tags were sequenced; 16,207 of these tags were found to represent unique sequences or tag families. Of the 304 most-abundant tags, 164 were assigned to a putative gene for subsequent functional grouping. The results (as determined according to the number of tags that identified genes encoding proteins required for these functions) indicated that the
C. neoformans
cells were actively engaged in protein synthesis, protein degradation, stress response, small-molecule transport, and signaling. In addition, a high level of energy requirement of the fungal cells was suggested by a large number of tags that matched putative genes for energy production. Taken together, these findings provide the first insight into the transcriptional adaptation of
C. neoformans
to the host environment and identify the set of fungal genes most highly expressed during cerebrospinal fluid infection.
MFα1
, the Gene Encoding the α Mating Pheromone of
Candida albicans
Authors: Panwar Sneh L. , Legrand Melanie , Dignard Daniel , Whiteway Malcolm , Magee Paul. T. 
Published: December 2003

ABSTRACT

Candida albicans
, the single most frequently isolated human fungal pathogen, was thought to be asexual until the recent discovery of the mating-type-like locus (
MTL
). Homozygous
MTL
strains were constructed and shown to mate. Furthermore, it has been demonstrated that opaque-phase cells are more efficient in mating than white-phase cells. The similarity of the genes involved in the mating pathway in
Saccharomyces cerevisiae
and
C. albicans
includes at least one gene (
KEX2
) that is involved in the processing of the α mating pheromone in the two yeasts. Taking into account this similarity, we searched the
C. albicans
genome for sequences that would encode the α pheromone gene. Here we report the isolation and characterization of the gene
MFα1
, which codes for the precursor of the α mating pheromone in
C. albicans
. Two active α-peptides, 13 and 14 amino acids long, would be generated after the precursor molecule is processed in
C. albicans
. To examine the role of this gene in mating, we constructed an
mfα1
null mutant of
C. albicans
. The
mfα1
null mutant fails to mate as
MTLα
, while
MTL
a
mfα1
cells are still mating competent. Experiments performed with the synthetic α-peptides show that they are capable of inducing growth arrest, as demonstrated by halo tests, and also induce shmooing in
MTL
a cells of
C. albicans
. These peptides are also able to complement the mating defect of an
MTLα kex2
mutant strain when added exogenously, thereby confirming their roles as α mating pheromones.
Sporangium-Specific Gene Expression in theOomycete Phytopathogen
Phytophthorainfestans
Authors: Kim Kyoung Su , Judelson Howard S. 
Published: December 2003

ABSTRACT

The
oomycete genus
Phytophthora
includes many of the world's
most destructive plant pathogens, which are generally disseminated by
asexual sporangia. To identify factors relevant to the biology of these
propagules, genes induced in sporangia of the potato late blight
pathogen
Phytophthora infestans
were isolated using
cDNA macroarrays. Of ∼1,900 genes known to be expressed in
sporangia, 61 were up-regulated >5-fold in sporangia versus
hyphae based on the arrays, including 17 that were induced>
100-fold. A subset were also activated by starvation and in a
nonsporulating mutant. mRNAs of some genes declined in abundance after
germination, while others persisted through the germinated zoospore
cyst stage. Functions were predicted for about three-quarters of the
genes, including potential regulators (protein kinases and
phosphatases, transcription factors, and G-protein subunits),
transporters, and metabolic enzymes. Predominant among the last were
several dehydrogenases, especially a highly expressed sorbitol
dehydrogenase that accounted for 3% of the mRNA. Sorbitol
dehydrogenase activity also rose during sporulation and several stress
treatments, paralleling the expression of the gene. Another interesting
metabolic enzyme resembled creatine kinases, which previously were
reported only in animals and trypanosomes. These results provide
insight into the transcriptional and cellular processes occurring in
sporangia and identify potential targets for crop protection
strategies.
Progression-Free Survival in Children With Optic Pathway Tumors: Dependence on Age and the Quality of the Response to Chemotherapy—Results of the First French Prospective Study for the French Society of Pediatric Oncology
Authors: Laithier Véronique , Grill Jacques , Le Deley Marie-Cécile , Ruchoux Marie-Madeleine , Couanet Dominique , Doz François , Pichon Fabienne , Rubie Hervé , Frappaz Didier , Vannier Jean-Paul , Babin-Boilletot Annie , Sariban Eric , Chastagner Pascal , Zerah Michel , Raquin Marie-Anne , Hartmann Olivier , Kalifa Chantal 
Published: December 2003

Purpose: To evaluate a strategy aimed at avoiding radiotherapy during first-line treatment of children with progressive optic pathway tumors (OPT), by exclusively administering multiagent chemotherapy during 16 months. Patients and Methods: Between 1990 and 1998, 85 children with progressive OPT were enrolled onto this multicenter nationwide trial. Chemotherapy alternating procarbazine plus carboplatin, etoposide plus cisplatin, and vincristine plus cyclophosphamide was given every 3 weeks. At the time of relapse or progression, second-line chemotherapy was authorized before recourse to radiotherapy. Results: Objective response rate (partial response [PR] + complete response [CR]) to chemotherapy was 42%. Five-year progression-free survival (PFS) and overall survival rates were 34% and 89%, respectively. The 5-year radiotherapy-free survival rate was 61%. In the multivariate analysis of the 85 patients that entered onto the study, factors associated with the risk of disease progression were age younger than 1 year at diagnosis (P = .047) and absence of neurofibromatosis type 1 (P = .035). In the multivariate analysis of the 74 patients that remained on study after the first cycle of chemotherapy, factors associated with the risk of disease progression were age younger than 1 year at diagnosis (P = .0053) and no objective response to chemotherapy (P = .0029). Three-year PFS was 44% in infants ≤ 1 year versus 66% in children older than 1 year. Three-year PFS was 53% in the absence of an objective response to chemotherapy versus 68% after a PR or CR. Conclusion: A significant proportion of children with OPT can avoid radiotherapy after prolonged chemotherapy. Deferring irradiation with chemotherapy protocols did not compromise overall survival of the entire population or visual function.
Analysis of Factors Associated With Outcome in Patients With Malignant Peritoneal Mesothelioma Undergoing Surgical Debulking and Intraperitoneal Chemotherapy
Authors: Feldman Andrew L. , Libutti Steven K. , Pingpank James F. , Bartlett David L. , Beresnev Tatiana H. , Mavroukakis Sharon M. , Steinberg Seth M. , Liewehr David J. , Kleiner David E. , Alexander H. Richard 
Published: December 2003

Purpose: Malignant mesothelioma (MM) arising in the peritoneal cavity is a rare neoplasm characterized by peritoneal progression and for which there are limited therapeutic options. We evaluated the peritoneal progression-free and overall survival (PFS and OS, respectively) for patients with peritoneal MM after surgical resection and regional chemotherapy.Patients and Methods: Forty-nine patients (28 males, 21 females; median age, 47 years; range, 16 to 76 years) with MM underwent laparotomy, tumor resection, continuous hyperthermic peritoneal perfusion with cisplatin (median dose 250 mg/m2), and a single postoperative intraperitoneal dwell of fluorouracil and paclitaxel (n = 35) on protocols approved by the Institutional Review Board. Standard techniques for actuarial analyses of potential prognostic variables (Kaplan-Meier method with two-tailed log-rank test and Cox proportional hazards model) were performed.Results: At a median potential follow-up of 28.3 months, median actuarial PFS is 17 months and actuarial OS is 92 months. Factors associated with improved PFS and OS by the Cox proportional hazards model were a history of previous debulking surgery, absence of deep tissue invasion, minimal residual disease after surgical resection (OS only), and age younger than 60 years (OS only).Conclusion: Surgical resection and regional chemotherapy for MM results in durable PFS and OS. Favorable outcome is associated with age, tumor biology (selection of patients with a history of previous debulking), lack of invasive tumor growth, and minimal residual disease after tumor resection.
Consultation With a Medical Oncologist Before Surgery and Type of Surgery Among Elderly Women With Early-Stage Breast Cancer
Authors: Keating Nancy L. , Landrum Mary Beth , Ayanian John Z. , Winer Eric P. , Guadagnoli Edward 
Published: December 2003

Purpose: Prior studies have documented variation in breast cancer treatment and care that does not follow guideline recommendations, particularly for elderly women. We assessed whether consultation with a medical oncologist before surgery was associated with use of definitive surgery, axillary node dissection, and type of surgery. Methods: We conducted a retrospective cohort study of a population-based sample of 9,630 women aged ≥ 66 years diagnosed with breast cancer during 1995 to 1996. We measured the adjusted proportion visiting a medical oncologist before surgery, identified factors associated with such visits, and assessed the association between visits with a medical oncologist and use of definitive surgery (mastectomy or breast-conserving surgery with radiation v breast-conserving surgery without radiation); axillary dissection; and breast-conserving surgery versus mastectomy among women undergoing definitive surgery. Results: Nineteen percent of women visited a medical oncologist before surgery; these women were younger, more often had larger or more poorly differentiated cancers, had more comorbid illnesses, and were treated more often at a teaching hospital (all P < .05). Women who saw a medical oncologist before surgery were more likely than others to undergo definitive surgery (adjusted odds ratio [OR], 1.28; 95% CI, 1.05 to 1.56) and axillary dissection (adjusted OR, 1.44; 95% CI, 1.19 to 1.73), but less likely to undergo breast-conserving surgery among women undergoing definitive surgery (OR, 0.84; 95% CI, 0.75 to 0.95). Conclusion: Elderly women who consulted with a medical oncologist before surgery were more likely to receive guideline-recommended care. Additional research is needed allow a better understanding of the quality and content of discussions that elderly women have with various providers about breast-conserving surgery and mastectomy.
Top-down regression of the avian oviduct during late oviposition in a small passerine bird
Authors: Williams T. D. , Ames C. E. 
Published: December 2003

SUMMARYEgg production in oviparous vertebrates is assumed to be costly but the physiological basis of any costs remains unknown. The avian oviduct is a highly differentiated linear organ, with five functionally specific regions. Here we show that the oviduct regresses rapidly `from the top down' as soon as the more proximal regions have completed their function but while the distal regions still retain an oviductal egg. In zebra finches Taeniopygia guttata, oviduct mass did not differ between early laying birds at the 1-egg stage compared with late-laying birds (with one remaining yolky follicle; dry mass, 151-167 mg). However, in birds with no remaining yolky follicles but with an oviductal egg, oviduct mass decreased to 94 mg (44%). Regression occurred unequally among different regions of the oviduct, with significant decreases in the proximal infundibulum/magnum and isthmus regions(59% and 40%, respectively), but no change in distal shell gland/vagina mass. The shell gland did not regress until after the last oviposition. Thus, the avian oviduct has a highly regulated size-function relationship consistent with a high maintenance energy cost for this organ. We suggest that oviduct function is a significant contributor to the physiological costs of egg production and might mediate individual variation in maternal effects associated with non-yolk components of egg quality (e.g. immunoglobulins,lysozyme).
Postprandial response of gastric pH in leopard sharks (Triakis semifasciata)and its use to study foraging ecology
Authors: Papastamatiou Yannis P. , Lowe Christopher G. 
Published: December 2003

SUMMARYChanges in gastric pH of leopard sharks Triakis semifasciata were quantified as an indicator of feeding frequency and ration size. Continuous in situ measurements of gastric pH were made in captive adult leopard sharks using an autonomous pH/temperature probe for periods ranging from 5-16 days. Instrumented sharks were fed meals of squid at different ration sizes. Gastric fluid samples were also taken from non-instrumented juvenile leopard sharks at different time intervals after feeding, and the pH measured to quantify effects of the pH probe in the stomach. Continuous in situmeasurements of pH show that empty stomachs have a low pH of 1.54±1.42(mean ± s.d.) and that feeding causes a rapid increase in pH to 3.11±0.71, followed by a gradual decrease back down to baseline levels. There was a positive relationship between changes in pH and meal size(r2=0.72, P=0.001). There were no significant differences in pH between continuous in situ and laboratory serial sample measurements. Together these findings indicate that gastric acid secretion may be continuous in leopard sharks, and that changes in gastric pH may be used to estimate feeding chronology, frequency and ration size of leopard sharks in the field.
Are melanized feather barbs stronger?
Authors: Butler Michael , Johnson Amy S. 
Published: December 2003

SUMMARYMelanin has been associated with increased resistance to abrasion,decreased wear and lowered barb breakage in feathers. But, this association was inferred without considering barb position along the rachis as a potentially confounding variable. We examined the cross-sectional area,breaking force, breaking stress, breaking strain and toughness of melanized and unmelanized barbs along the entire rachis of a primary feather from an osprey (Pandion haliaetus). Although breaking force was higher for melanized barbs, breaking stress (force divided by cross-sectional area) was greater for unmelanized barbs. But when position was considered, all mechanical differences between melanized and unmelanized barbs disappeared. Barb breaking stress, breaking strain and toughness decreased, and breaking stiffness increased, distally along the rachis. These proximal-distal material property changes are small and seem unlikely to affect flight performance of barbs. Our observations of barb bending, breaking and morphology, however,lead us to propose a design principle for barbs. We propose that, by being thicker-walled dorso-ventrally, the barb's flexural stiffness is increased during flight; but, by allowing for twisting when loaded with dangerously high forces, barbs firstly avoid failure by bending and secondly avoid complete failure by buckling rather than rupturing.
Adaptive function of soil consumption: anin vitrostudy modeling the human stomach and small intestine
Authors: Dominy Nathaniel J. , Davoust Estelle , Minekus Mans 
Published: December 2003

SUMMARYDespite occurring in a wide variety of taxa, deliberate soil consumption(geophagy) is a poorly understood behavior. In humans, geophagy is sometimes considered aberrant or a sign of metabolic dysfunction. However, geophagy is normally assigned an adaptive function in nonhuman primates and various other organisms. One hypothesis submits that clay-rich soil adsorbs intestinal insults, namely plant metabolites or diarrhoea-causing enterotoxins. Here we test the capacity of kaolin, a commonly ingested clay, to adsorb quinine (an alkaloid) and two types of tannin (digestion-inhibitors). Trials were conducted in vitro using the TNO Intestinal Model, a device that closely simulates digestion by the human stomach and small intestine. Kaolin reduced the bioavailability of each compound by ≤30%. However, because we could not replicate clay-epithelial adhesion and reduced motility, these results may underestimate adsorption in vivo. We also show that kaolin fails to render calcium oxalate soluble. We conclude that gastrointestinal adsorption is the most plausible function of human geophagy. Adaptive advantages include greater exploitation of marginal plant foods and reduced energetic costs of diarrhoea, factors that could account for the high frequency of geophagy in children and pregnant women across the tropics.