bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environment temperature affects cell proliferation in the spinal cord and brain of juvenile turtles
Authors: Radmilovich Milka , Fernández Anabel , Trujillo-Cenóz Omar 
Published: July 2003

SUMMARY
The spinal cords and brains - comprising dorsal cortex (DC), medial cortex(MC) and diencephalon (Dien) - of juvenile turtles acclimated to warm temperature [27-30°C; warm-acclimated turtles (WATs)] revealed higher density values of bromodeoxyuridine-labeled cells (BrdU-LCs) than those acclimated to a cooler environment [5-14°C; cold-acclimated turtles(CATs)]. Both populations were under the influence of the seasonal daily light-dark rhythms. Pronounced differences between WATs and CATs (independent t-test; confidence level, P&lt;0.01) were found in the central area of the spinal gray matter and in the ependymal epithelium lining the brain ventricles. Forebrain regions (DC, MC and Dien) also revealed significant differences between WATs and CATs (independent t-test;confidence level, P&lt;0.01-0.05). Unexplored biological clocks that may be affecting cell proliferation were equalized by performing paired experiments involving one WAT and one CAT. Both animals were injected on the same day at the same time and both were sacrificed 24 h later. These experiments confirmed that a warm environment increased cell proliferation in the CNS of turtles. Double- and triple-labeling experiments involving anti-BrdU antibody together with anti-glial protein antibodies revealed that temperature modulates not only cell populations expressing glial markers but also other cells that do not express them. As expected, in the case of short post-injection (BrdU) surviving time points, no cells were found colabeling for BrdU and NeuN (neuronal marker). The probable direct effect of temperature on the cell division rate should be analyzed together with potential indirect effects involving increased motor activity and increased food intake. The fate of the increased BrdU-LCs (death, permanence as progenitor cells or differentiation following neuronal or glial lines) remains a matter for further investigation. Results are discussed in the light of current opinions concerned with post-natal neurogenesis in vertebrates.
Evolution of the coordinate regulation of glycolytic enzyme genes by hypoxia
Authors: Webster Keith A. 
Published: July 2003

SUMMARYTwo billion years of aerobic evolution have resulted in mammalian cells and tissues that are extremely oxygen-dependent. Exposure to oxygen tensions outside the relatively narrow physiological range results in cellular stress and toxicity. Consequently, hypoxia features prominently in many human diseases, particularly those associated with blood and vascular disorders,including all forms of anemia and ischemia. Bioenergetic enzymes have evolved both acute and chronic oxygen sensing mechanisms to buffer changes of oxygen tension; at normal PO oxidative phosphorylation is the principal energy supply for eukaryotic cells, but when the PO falls below a critical mark metabolic switches turn off mitochondrial electron transport and activate anaerobic glycolysis. Without this switch cells would suffer an immediate energy deficit and death at low PO. An intriguing feature of the switching is that the same conditions that regulate energy metabolism also regulate bioenergetic genes, so that enzyme activity and transcription are regulated simultaneously,albeit with different time courses and signaling pathways. In this review we explore the pathways mediating hypoxia-regulated glycolytic enzyme gene expression, focusing on their atavistic traits and evolution.
Aerodynamic force generation and power requirements in forward flight in a fruit fly with modeled wing motion
Authors: Sun Mao , Wu Jiang Hao 
Published: July 2003

SUMMARYAerodynamic force generation and power requirements in forward flight in a fruit fly with modeled wing motion were studied using the method of computational fluid dynamics. The Navier-Stokes equations were solved numerically. The solution provided the flow velocity and pressure fields, from which the vorticity wake structure and the unsteady aerodynamic forces and torques were obtained (the inertial torques due to the acceleration of the wing-mass were computed analytically). From the flow-structure and force information, insights were gained into the unsteady aerodynamic force generation. On the basis of the aerodynamic and inertial torques, the mechanical power was obtained, and its properties were investigated.The unsteady force mechanisms revealed previously for hovering (i.e. delayed stall, rapid acceleration at the beginning of the strokes and fast pitching-up rotation at the end of the strokes) apply to forward flight. Even at high advance ratios, e.g. J=0.53-0.66 (J is the advance ratio), the leading edge vortex does not shed (at such advance ratios, the wing travels approximately 6.5 chord lengths during the downstroke).At low speeds (J≈0.13), the lift (vertical force) for weight support is produced during both the down- and upstrokes (the downstroke producing approximately 80% and the upstroke producing approximately 20% of the mean lift), and the lift is contributed mainly by the wing lift; the thrust that overcomes the body drag is produced during the upstroke, and it is contributed mainly by the wing drag. At medium speeds (J≈0.27),the lift is mainly produced during the downstroke and the thrust mainly during the upstroke; both of them are contributed almost equally by the wing lift and wing drag. At high speeds (J≈0.53), the lift is mainly produced during the downstroke and is mainly contributed by the wing drag; the thrust is produced during both the down- and upstrokes, and in the downstroke, is contributed by the wing lift and in the upstroke, by the wing drag.In forward flight, especially at medium and high flight speeds, the work done during the downstroke is significantly greater than during the upstroke. At advance ratios J≈0.13, 0.27 and 0.53, the work done during the downstroke is approximately 1.6, 2.8 and 4.2 times as much as that during the upstroke, respectively.At J=0 (hovering), the body-mass-specific power is approximately 29 W kg-1; at J=0.13 and 0.27, the power is approximately 10% less than that of hovering; at J=0.40, the power is approximately the same as that of hovering; when J is further increased, the power increases sharply. The graph of power against flying speeds is approximately J-shaped.From the graph of power against flying speeds, it is predicted that the insect usually flies at advance ratios between zero and 0.4, and for fast flight, it would fly at an advance ratio between 0.4 and 0.53.
Effect of a mono-specific algal diet on immune functions in two bivalve species -Crassostrea gigasandRuditapes philippinarum
Authors: Delaporte Maryse , Soudant Philippe , Moal Jeanne , Lambert Christophe , Quéré Claudie , Miner Philippe , Choquet Gwénaëlle , Paillard Christine , Samain Jean-François 
Published: July 2003

SUMMARYThe impact of diets upon the fatty acid composition of haemocyte polar lipids and consequently upon immune parameters has been tested in the oyster Crassostrea gigas and the clam Ruditapes philippinarum. Oysters and clams were fed each of three cultured algae: Chaetoceros calcitrans, which is rich in 20:5(n-3) and 20:4(n-6) and poor in 22:6(n-3) fatty acids; T-Iso (Isochrysis sp.), which is rich in 22:6(n-3) and deficient in 20:5(n-3) and 20:4(n-6); and Tetraselmis suecica, which is deficient in 22:6(n-3) and contains only small amounts of 20:5(n-3) and 20:4(n-6).Fatty acid composition of haemocyte polar lipids was greatly affected by the diet. Oysters and clams fed C. calcitrans maintained a higher proportion of 20:5(n-3) and 20:4(n-6) in their haemocyte polar lipids, while these polyunsaturated fatty acids decreased drastically for animals fed T-Iso. However, the T-Iso diet maintained 22:6(n-3) in haemocyte polar lipids of both species. Higher 20:5(n-3) and 20:4(n-6)contents in diets appeared to have a positive effect upon total haemocyte count, granulocyte percentage, phagocytic rate and oxidative activity of clam haemocytes. Similarly, a positive effect of 20:5(n-3) on oxidative activity of oyster haemocytes was observed but to a lesser extent than in clams. Interestingly, when oyster haemocytes are submitted to a stressful condition,a positive effect of a higher dietary 22:6(n-3) content on the phagocytic rate was noticed.
Thermal acclimation of surfactant secretion and its regulation by adrenergic and cholinergic agonists in type II cells isolated from warm-active and torpid golden-mantled ground squirrels,Spermophilus lateralis
Authors: Ormond Carol J. , Orgeig Sandra , Daniels Christopher B. , Milsom William K. 
Published: July 2003

SUMMARYHomeothermic mammals experience pulmonary surfactant dysfunction with relatively small fluctuations in body temperature. However, ground squirrels survive dramatic changes in body temperature during hibernation, when body temperature drops from 37°C to 0-5°C during prolonged torpor bouts. Using type II cells isolated from both warm-active and torpid squirrels, we determined the effect of assay temperature, autonomic agonists and torpor on surfactant secretion. Basal secretion was significantly higher in type II cells isolated from torpid squirrels compared with warm-active squirrels when assayed at the body temperature of the animal from which they were isolated(4°C and 37°C, respectively). A change in assay temperature significantly decreased surfactant secretion. However, the change in secretory rate between 37°C and 4°C was less than expected if due to temperature alone (Q10 range=0.8-1.2). Therefore, the surfactant secretory pathway in squirrel type II cells demonstrates some temperature insensitivity. When incubated at the body temperature of the animal from which the cells were isolated, the adrenergic agonist, isoproterenol, significantly increased surfactant secretion in both warm-active and torpid squirrel type II cells. However, the cholinergic agonist, carbamylcholine chloride, only increased secretion in torpid squirrel type II cells when incubated at 4°C. Torpor did not affect basal cAMP production from isolated type II cells. However, the production of cAMP appears to be upregulated in response to isoproterenol in torpid squirrel type II cells. Thus, at the cellular level, both the secretory and regulatory pathways involved in surfactant secretion are thermally insensitive. Upregulating basal secretion and increasing the sensitivity of type II cells to cholinergic stimulation may be adaptative characteristics of torpor that enable type II cells to function effectively at 0-5°C.
Screening of second messengers involved in photocyte bioluminescence control of three ophiuroid species (Ophiuroidea: Echinodermata)
Authors: Vanderlinden C. , Dewael Y. , Mallefet J. 
Published: July 2003

SUMMARYWe investigated the effects of cyclic nucleotides (cGMP and cAMP) and inositol triphosphate/diacylglycerol pathways on the KCl-induced luminescence control of the ophiuroid species Amphiura filiformis, Ophiopsila aranea and Ophiopsila californica. Results show that dibutyrylcGMP, the cGMP analogue, and sodium nitroprusside, the guanylyl cyclase activator, had no effect on the luminescence of O. aranea and O. californica. On the other hand, cGMP could be involved in an inhibitory control in A. filiformis. Dibutyryl-cAMP, the cAMP analogue, and forskolin, the adenylyl cyclase activator, had no effect on maximal light emission, but the adenylyl cyclase inhibitors MDL-12,330A and SQ22,536 affected the kinetics of light production in both Ophiopsilaspecies and strongly reduced KCl-induced luminescence in A. filiformis and O. aranea, suggesting cAMP pathway involvement in photogenesis. The phospholipase C inhibitor U-73122 also strongly reduced KCl-induced luminescence in all three species but this effect seems to be unspecific since U-73343, the inactive analogue of U-73122, equally inhibited photogenesis. Therefore, the results suggest that luminescence control of A. filiformis, O. aranea and O. californica is mediated by cAMP in synergy with calcium.
Effects of temperature and extracellular pH on metabolites: kinetics of anaerobic metabolism in resting muscle by 31P- and 1H-NMR spectroscopy
Authors: Vezzoli Alessandra , Gussoni Maristella , Greco Fulvia , Zetta Lucia 
Published: July 2003

SUMMARYEnvironmental stress, such as low temperature, extracellular acidosis and anoxia, is known to play a key role in metabolic regulation. The aim of the present study was to gain insight into the combined temperature-pH regulation of metabolic rate in frog muscle, i.e. an anoxia-tolerant tissue. The rate of exergonic metabolic processes occurring in resting isolated muscles was determined at 15°C and 25°C as well as at extracellular pH values higher (7.9), similar (7.3) and lower (7.0) than the physiological intracellular pH. 31P and 1H nuclear magnetic resonance spectroscopy high-resolution measurements were carried out at 4.7 T in isolated frog (Rana esculenta) gastrocnemius muscle during anoxia to assess, by means of reference compounds, the concentration of all phosphate metabolites and lactate. Intra- and extracellular pH was also determined.In the range of examined temperatures (15-25°C), the temperature dependence of anaerobic glycolysis was found to be higher than that of PCr depletion (Q10=2.3). High-energy phosphate metabolism was confirmed to be the initial and preferential energy source. The rate of phosphocreatine hydrolysis did not appear to be affected by extracellular pH changes. By contrast, independent of the intracellular pH value, at the higher temperature(25°C) a lowering of the extracellular pH from 7.9 to 7.0 caused a depression in lactate accumulation. This mechanism was ascribed to the transmembrane proton concentration gradient. This parameter was demonstrated to regulate glycolysis, probably through a reduced lactate efflux, depending on the activity of the lactate-H+ co-transporter.The calculated intracellular buffer capacity was related to intra- and extracellular pH and temperature. At the experimental extracellular pH of 7.9 and at a temperature of 15°C and 25°C, calculated intracellular buffering capacity was 29.50 μmol g-1 pH unit-1 and 69.98 μmol g-1 pH unit-1, respectively.
Species-specific effects of single sensillum ablation on mating position inDrosophila
Authors: Acebes Angel , Cobb Matthew , Ferveur Jean-François 
Published: July 2003

SUMMARYDipteran insects show a wide range of species-specific mating positions. Interspecific transitions from one position to another may reflect sexual or natural selection, or be pleiotropic consequences of other genetic changes. Like many cyclorrhaphan flies, Drosophila species mate with the male on the back of the female, positioned centrally. Mechanosensory sensilla on the male genitalia of three species of the melanogaster species sub-group of Drosophila have species-specific effects on mating position and on courtship success: ablation of a single pair of bristles on the genital claspers of D. melanogaster males halved homotypic mating success, and unilateral ablation produced a contralateral asymmetry in the male's mating posture. Ablation of mechanoreceptors on the male genital lateral plate affected mating posture less radically and had no effect on mating frequency. Surprisingly, ablation of sensilla on the claspers of D. simulans and D. sechellia males showed no effect on homotypic mating. A similar result was found for D. melanogaster × D. simulans hybrid males. The existence of major differences in the sensory bases of mating position and copulation success in closely related species shows how differing mating positions may have evolved and underlines the need for detailed functional studies in studying the evolution of insect genitalia:homologous structures may serve different functions in different species.
Flexural stiffness in insect wings I. Scaling and the influence of wing venation
Authors: Combes S. A. , Daniel T. L. 
Published: July 2003

SUMMARYDuring flight, many insect wings undergo dramatic deformations that are controlled largely by the architecture of the wing. The pattern of supporting veins in wings varies widely among insect orders and families, but the functional significance of phylogenetic trends in wing venation remains unknown, and measurements of the mechanical properties of wings are rare. In this study, we address the relationship between venation pattern and wing flexibility by measuring the flexural stiffness of wings (in both the spanwise and chordwise directions) and quantifying wing venation in 16 insect species from six orders. These measurements show that spanwise flexural stiffness scales strongly with the cube of wing span, whereas chordwise flexural stiffness scales with the square of chord length. Wing size accounts for over 95% of the variability in measured flexural stiffness; the residuals of this relationship are small and uncorrelated with standardized independent contrasts of wing venation characters. In all species tested, spanwise flexural stiffness is 1-2 orders of magnitude larger than chordwise flexural stiffness. A finite element model of an insect wing demonstrates that leading edge veins are crucial in generating this spanwise-chordwise anisotropy.
Flexural stiffness in insect wings II. Spatial distribution and dynamic wing bending
Authors: Combes S. A. , Daniel T. L. 
Published: July 2003

SUMMARYThe dynamic, three-dimensional shape of flapping insect wings may influence many aspects of flight performance. Insect wing deformations during flight are largely passive, and are controlled primarily by the architecture and material properties of the wing. Although many details of wing structure are well understood, the distribution of flexural stiffness in insect wings and its effects on wing bending are unknown. In this study, we developed a method of estimating spatial variation in flexural stiffness in both the spanwise and chordwise direction of insect wings. We measured displacement along the wing in response to a point force, and modeled flexural stiffness variation as a simple mathematical function capable of approximating this measured displacement. We used this method to estimate flexural stiffness variation in the hawkmoth Manduca sexta, and the dragonfly Aeshna multicolor. In both species, flexural stiffness declines sharply from the wing base to the tip, and from the leading edge to the trailing edge; this variation can be approximated by an exponential decline. The wings of M. sexta also display dorsal/ventral asymmetry in flexural stiffness and significant differences between males and females. Finite element models based on M. sexta forewings demonstrate that the measured spatial variation in flexural stiffness preserves rigidity in proximal regions of the wing,while transferring bending to the edges, where aerodynamic force production is most sensitive to subtle changes in shape.
A Simple and Facile Chemo- and Regioselective Deprotection of Acetonides Using Silica Supported Sodium Hydrogen Sulfate as a Heterogeneous Catalyst
Authors: Mahender G , Ramu R , Ramesh C , Das Biswanath 
Published: July 2003

Abstract
Silica supported sodium hydrogen sulfate (NaHSO4·SiO2) has been found to be an efficient heterogeneous catalyst for chemo- and regioselective deprotection of acetonides at room temperature to produce the corresponding diols in excellent yields.
A Phthalocyanine Producing Green, Ocher, and Red Colors Depending on the Central Metals
Authors: Fukuda Takamitsu , Ono Kosuke , Homma Shigetsugu , Kobayashi Nagao 
Published: July 2003

Abstract
Metal complexes of a highly deformed 1,4,8,11,15,18,22,25-octaphenylphthalocyanine have been synthesized, and found to show various colors ranging from bright green, ocher, and red depending on the central metal employed.
Efficient and Rapid One-pot Conversions of Aldehydes into Nitriles and Ketones into Amides Using Silica Chloride under Microwave Irradiation
Authors: Srinivas K V N S , Mahender I , Das Biswanath 
Published: July 2003

Abstract
Under solvent free conditions, several aldehydes and ketones were efficiently and rapidly converted into the corresponding nitriles and amides respectively by treatment with hydroxylamine hydrochloride under microwave irradiation using silica chloride as catalyst. The yields of the products were very high and the time required for their preparation was very short compared to conventional heating experiments.
Crystal Structure of 1-Butyl-3-methylimidazolium Chloride. A Clue to the Elucidation of the Ionic Liquid Structure
Authors: Saha Satyen , Hayashi Satoshi , Kobayashi Akiko , Hamaguchi Hiro-o 
Published: July 2003

Abstract
A single crystal of 1-butyl-3-methylimidazolium chloride [bmim]Cl, a prototype ionic liquid, has successfully been prepared and an X-ray crystallographic analysis has been performed. It reveals the presence of a hydrogen bonding network involving the chloride anion and the ring as well as the n-butyl hydrogen atoms, a strong hydrophobic interaction between the two n-butyl groups of the [bmim] cations, and a unique corrugated sheets structure of the imidazolium rings. Considering the similarity of the Raman spectra of crystalline and liquid states, we suspect that the three dimensional structure determined in the present study also exist, at least partially, in the ionic liquid state.
Deuterium Migration Mechanism in Chiral Thiolactam Formation by Neutron Diffraction Analysis
Authors: Hosoya Takaaki , Uekusa Hidehiro , Ohashi Yuji , Ohhara Takashi , Kimura Hiroyuki , Noda Yukio 
Published: July 2003

Abstract
The single-crystal neutron diffraction revealed that in the process of photo-induced β-thiolactam formation from N,N-dibenzyl-1-cyclohexenecarbothioamide a deuterium atom bonded to the benzyl carbon atom is transferred to the intramolecular cyclohexene carbon to occupy the equatorial position of the produced cyclohexyl ring.
Synthesis of β-Thiophene-Substituted 21,23-Dithiaporphyrins
Authors: Agarwal Neeraj , Mishra Sarada P , Kumar A , Ravikanth M 
Published: July 2003

Abstract
β-Thiophene-substituted 21,23-dithiaporphyrins with substituents like methyl and phenyl groups were synthesized and characterized.
Blue-shifted Hydrogen Bonds with Proton-donors Incapable of Rehybridization
Authors: Wang Jin-Ti , Feng Yong , Liu Lei , Li Xiao-Song , Guo Qing-Xiang 
Published: July 2003

Abstract
Blue-shifted hydrogen bonds were found for F–He–H···Y (Y = N2, CO, and He) systems where the proton-donor (He) was incapable of rehybridization. This finding indicated that rehybridization is not a generally applicable driving force for the blue shift.
Formation of a Novel Polymeric Cadmium(II) Complex Bridged by Sulfur and Thiocyanato Ions
Authors: Li Sheng-Li , Wu Jie-Ying , Zhang Xuan-Jun , Tian Yu-Peng , Jiang Min-Hua , Chen Zu-Yao , Usman Anwar , Fun Hoong-Kun 
Published: July 2003

Abstract
The title complex, {[N(CH3)4]2[Cd(SCN)2S]}n, was prepared by self-assembling from the reaction of a methanol/water (volume ratio, 1/1) solution containing cadmium(II) thiocyanate with equivalent amount of tetramethylammonium thiocyanate. The result of single X-ray determination for the complex reveals that a novel polymeric cadmium(II) complex bridged by sulfur and thiocyanato ions was obtained, which formed a two-dimensional (2D) structure.
Photostimulated Long-lasting Phosphorescence in Rare-earth-doped Glasses
Authors: Qiu Jianrong , Jiang Xiongwei , Zhu Congshan , Si Jinhai , Li Chengyu , Su Qiang , Hirao Kazuyuki 
Published: July 2003

Abstract
Tb3+-doped glass sample emits bright and long-lasting phosphorescence after irradiation by an 800-nm femtosecond pulsed laser. Long-lasting phosphorescence is observed once again after further excitation by 365-nm UV light when the femtosecond laser-induced long-lasting phosphorescence cannot be detected.