bluuebunny/crossref_metadata_2025_split huggingface dataset:
The nature of resistance to Dectes texanus (Col., Cerambycidae) in wild sunflower, Helianthus annuus
Authors: Michaud J. P. , Grant A. K. 
Published: March 2009

AbstractThe longhorned beetle Dectes texanus LeConte is a serious pest of cultivated sunflowers, Helianthus annuus L. and soybeans, Glycine max (L.), throughout much of the American midwest. Significant yield losses arise from the pre‐harvest lodging of plants when mature larvae girdle the base of stalks in preparation for overwintering. We investigated possible reasons why infestation of wild H. annuus by D. texanus is remarkably rare, whereas 80–90% of plants may be infested in fields of cultivated varieties. When caged on wild sunflower plants in the field, laboratory‐reared, gravid females fed less and made significantly fewer ovipositional punctures than they did when subsequently caged on a cultivated plant. Furthermore, only 18.4% of ovipunctures in wild plants resulted in an egg being laid, compared with 44.9% in cultivated plants, suggesting that additional resistance factors reduce the probability of eggs being laid during ovipositor insertion. Female behaviour was not affected by adult diet prior to testing (wild vs. cultivated H. annuus petioles), nor was there any difference in response between females obtained as larvae from cultivated sunflower or from soybean. Petioles of wild H. annuus exuded more than four times the weight of resinous material when severed as did those of cultivated plants, were significantly less succulent as determined by water content, and required significantly more force to penetrate the epidermis in a standardized puncture test. We conclude that a combination of physical and chemical properties of wild H. annuus confers substantial resistance to oviposition by D. texanus and that this natural antixenosis has been inadvertently diminished in the course of breeding cultivated varieties.
Pea weevil, Bruchus pisorum L. (Coleoptera: Bruchidae), resistance in Pisum sativum×Pisum fulvum interspecific crosses
Authors: Clement S. L. , McPhee K. E. , Elberson L. R. , Evans M. A. 
Published: March 2009

AbstractThe pea weevil, Bruchus pisorum (L.), is one of the most intractable pest problems of cultivated pea, Pisum sativum L., in the world. This study investigated the transfer of pea weevil resistance from two accessions (PI 595946, PI 343955) of wild pea, Pisum fulvum Sibth. & Sm., to interspecific populations derived from crossing these accessions with a weevil‐susceptible pea cultivar (‘Alaska 81’). Partial life tables characterized weevil stage‐specific mortality and survivorship on parents and interspecific progeny in two glasshouse trials. Larval mortality rates on pods (F3 plants) of several F2:3 families were between 36.0% and 52.9%. These means were statistically similar to mean mortality rates on pods of resistant parents (45.4% and 46.2%), but significantly greater than mean rates on the susceptible parent (1.2% and 10.6%). Pod surface characteristics contributed to high neonate larval mortality on pods of resistant parents and interspecific progeny. Seed resistance was not broadly transferred to interspecific progeny [revealed by high weevil survivorship in seeds (means mostly >80%) and high seed damage ratings of 3–5 where ratings of 1–2 denote resistance (production of resistant seed averaged 4.2% to 22.8%)]. Estimates of total weevil mortality on pods and seeds of eight F2:3 families were 50–70%. Thus, weevil resistance in the Pisum secondary gene pool can be transferred to interspecific progeny, thereby providing a potential avenue to develop weevil‐resistant pea cultivars.
EFFECTS OF THORACIC EPIDURAL ANAESTHESIA ON CARDIAC REPOLARIZATION
Authors: Owczuk Radoslaw , Steffek Mariusz , Wujtewicz Magdalena A , Szymanowicz Wiktor , Twardowski Pawel , Marjanski Tomasz , Wojciechowski Jacek , Zienciuk Agnieszka , Rzyman Witold , Wujtewicz Maria 
Published: March 2009

SUMMARY

Prolongation of the QT interval is associated with a risk of life‐threatening cardiac arrhythmias. In the present study, we examined whether reversible blockade of preganglionic sympathetic fibres of the heart, achieved by thoracic epidural anaesthesia, affects cardiac repolarization and thus confers an anti‐arrhythmic effect.
Fifty‐two men, aged between 28 and 65 years, were included in the study: 28 were patients scheduled for thoracic epidural anaesthesia (Group T) and 24 were patients scheduled for lumbar epidural anaesthesia (Group L). Epidural blockade was achieved with 0.5% isobaric bupivacaine solution. Measurements were taken from electrocardiogram fragments obtained before epidural anaesthesia and after detection of blockade (T1 or T8 segment sensory block in Groups T and L, respectively). Correction of the QT interval was calculated using Bazett's formula (QTcb), Fridericia's correction (QTcf) and the Framingham formula (QTcF). Transmural dispersion of repolarization (TDR) was determined using the Tpeak – Tend time, where Tpeak is the peak of the T wave and Tend is the end of the T wave.
Significant shortening of the QTcb interval and TDR was detected after blockade in Group T. However, there were no changes in the ECG parameters in Group L.
In conclusion, reversible blockade of preganglionic sympathetic fibres to the heart, achieved by thoracic epidural anaesthesia, results in a reduction in QTcb, as well as the TDR. These changes may explain the anti‐arrhythmic action seen with central blockade.
CHROMIUM PICOLINATE INHIBITS RESISTIN SECRETION IN INSULIN‐RESISTANT 3T3‐L1 ADIPOCYTES VIA ACTIVATION OF AMP‐ACTIVATED PROTEIN KINASE
Authors: Wang Yi‐Qun , Dong Yi , Yao Ming‐Hui 
Published: March 2009

SUMMARY

Chromium picolinate (CrPic) has been recommended as an alternative therapeutic regimen for Type 2 diabetes mellitus (T2DM). However, the molecular mechanism underlying the action of CrPic is poorly understood.
Using normal and insulin‐resistant 3T3‐L1 adipocytes, we examined the effects of CrPic on the gene transcription and secretion of adiponectin and resistin. In addition, using immunoblotting, ELISA and real‐time reverse transcription–polymerase chain reaction (RT‐PCR), we investigated the effects of 10 nmol/L CrPic for 24 h on AMP‐activated protein kinase (AMPK) to determine whether this pathway contributed to the regulation of adiponectin and resistin expression and secretion.
Chromium picolinate did not modulate the expression of adiponectin and resistin; however, it did significantly inhibit the secretion of resistin, but not adiponectin, by normal and insulin‐resistant 3T3‐L1 adipocytes in vitro. Furthermore, although CrPic markedly elevated levels of phosphorylated AMPK and acetyl CoA carboxylase in 3T3‐L1 adipocytes, it had no effect on the levels of AMPK α‐1 and α‐2 mRNA transcripts. Importantly, inhibition of AMPK by 2 h pretreatment of cells with 20 µmol/L compound C completely abolished the CrPic‐induced suppression of resistin secretion.
In conclusion, the data suggest that CrPic inhibits resistin secretion via activation of AMPK in normal and insulin‐resistant 3T3‐L1 adipocytes.
HYPOXIA‐INDUCIBLE FACTOR‐1 IMPROVES THE ACTIONS OF POSITIVE INOTROPIC AGENTS IN STUNNED CARDIAC MYOCYTES
Authors: Tan Tao , Luciano Jason A , Scholz Peter M , Weiss Harvey R 
Published: March 2009

SUMMARY

In the present study, we tested hypothesis that upregulation of hypoxia‐inducible factor‐1 (HIF‐1) would improve the actions of positive inotropic agents in cardiac myocytes after simulated ischaemia–reperfusion (I/R).
Hypoxia‐inducible factor‐1α was upregulated with deferoxamine (150 mg/kg per day for 2 days). Rabbit cardiac myocytes were subjected to simulated ischaemia (15 min, 95% N2–5% CO2) and reperfusion (re‐oxygenation) and compared with control myocytes. Cell contraction and calcium transients were measured at baseline and after forskolin (10−7 and 10−6 mol/L) or ouabain (10−5 and 10−4 mol/L).
Under control conditions, high‐dose forskolin and ouabain increased percentage shortening by 20 and 18%, respectively. Deferoxamine‐treated control myocytes responded similarly. In stunned myocytes, forskolin and ouabain did not significantly increase shortening (increases of 8% and 9%, respectively). Deferoxamine restored the effects of forskolin (+26%) and ouabain (+28%) in stunning. The results for maximum shortening and relaxation rates were similar. The increased calcium transients caused by forskolin and ouabain were also depressed in stunned myocytes, but were maintained by HIF‐1 upregulation.
These results suggest that simulated I/R impaired the functional and calcium transient effects of positive inotropic agents. Upregulation of HIF‐1 protects cardiac myocyte function after I/R by maintaining calcium release.
ANTI‐APOPTOTIC EFFECT OF HEAT SHOCK PROTEIN 90 ON HYPOXIA‐MEDIATED CARDIOMYOCYTE DAMAGE IS MEDIATED VIA THE PHOSPHATIDYLINOSITOL 3‐KINASE/AKT PATHWAY
Authors: Wang Wei , Peng Yizhi , Wang Yuanyuan , Zhao Xiaohui , Yuan Zhiqiang 
Published: March 2009

SUMMARY

Hypoxia‐induced cardiomyocyte apoptosis contributes significantly to cardiac dysfunction following trauma, shock and burn injury. There is evidence that heat shock protein (HSP) 90 is anti‐apoptotic in cardiomyocytes subjected to a variety of apoptotic stimuli. Because HSP90 acts as an upstream regulator of the serine/threonine protein kinase Akt survival pathway during cellular stress, we hypothesized that HSP90 exerts a cardioprotetive effect via the phosphatidylinositol 3‐kinase (PI3‐K)/Akt pathway.
Neonatal rat cardiomyocytes were subjected to normoxia or hypoxia in the absence or presence of the HSP90 inhibitor geldanamycin (1 µg/mL). Cardiomyocyte apoptosis was assessed by release of lactate dehydrogenase (LDH), terminal deoxyribonucleotidyl transferase‐mediated dUTP–digoxigenin nick end‐labelling (TUNEL) staining and caspase 3 activity. Expression of HSP90, Akt, Bad and cytochrome c release was determined by western blot analysis.
Following exposure of cells to hypoxia, HSP90 was markedly elevated in a time‐dependent manner, reaching a peak at 6 h (eightfold increase). Geldanamycin significantly increased hypoxia‐induced release of LDH by 114%, the percentage of apoptotic cardiomyocytes by 102% and caspase 3 activity by 78%. Pretreatment of cells with geldanamycin also suppressed phosphorylation of both Akt and its downstream target Bad, but promoted the mitochondrial release of cytochrome c.
In conclusion, HSP90 activity is enhanced in cardiomyocytes following hypoxic insult. The anti‐apoptotic effect of HSP90 on cardiomyocytes subjected to hypoxia is mediated, at least in part, by the PI3‐K/Akt pathway.
EFFECTS OF SODIUM FERULATE ON HUMAN OSTEOARTHRITIC CHONDROCYTES AND OSTEOARTHRITIS IN RATS
Authors: Shang Liang , Qin Jun , Chen Liao‐Bin , Liu Bao‐Xin , Jacques Magdalou , Wang Hui 
Published: March 2009

SUMMARY

Oxidation, inflammation and apoptosis are involved in the aetiology and pathology of osteoarthritis (OA). Sodium ferulate (SF) has been demonstrated to have anti‐oxidant, anti‐inflammatory and anti‐apoptotic actions in cardiovascular, hepatic and diabetic disorders. These findings suggest that SF may have beneficial effects on OA. Therefore, present study investigated the effects of SF in an in vivo rat OA model, as well as in vitro in human OA chondrocytes.
Rats were divided into the following groups: (i) an untreated control group; (ii) papain‐induced OA; (iii) OA rats treated with 0.1 or 0.5% SF; and (iv) normal rats injected with 0.5% SF intra‐articularly. Human chondrocytes from OA patients were cultured before being stimulated with 2 ng/mL interleukin‐1β and subsequently treated with SF (125, 250 and 500 µmol/L). The effects of SF were evaluated both in vivo and in vitro.
In OA rats, SF treatment dose‐dependently reversed pathological changes in OA cartilage, decreased BAX‐immunopositive chondrocytes and increased Bcl‐2‐immunopositive chondrocytes. Both in vivo and in vitro analyses demonstrated a significant decrease in matrix metalloproteinase‐1 and an increase in tissue‐specific inhibitor of metalloproteinase‐1. In vitro, SF enhanced chondrocyte proliferation and decreased nitric oxide production and apoptosis.
The results demonstrate that SF dose‐dependently suppresses pathological processes in both in vitro and in vivo OA models. Thus, SF could be a therapeutic strategy for the treatment of OA.
EPIGALLOCATECHIN‐3‐GALLATE ATTENUATES CARDIAC HYPERTROPHY IN HYPERTENSIVE RATS IN PART BY MODULATION OF MITOGEN‐ACTIVATED PROTEIN KINASE SIGNALS
Authors: Chen Dan‐Dan , Dong Yu‐Gang , Liu Dan , He Jian‐Gui 
Published: March 2009

SUMMARY

It has been demonstrated that epigallocatechin‐3‐gallate (EGCG) inhibits cardiac hypertrophy through its antihypertensive and anti‐oxidant effects. However, the underlying molecular mechanism is not clear.
In the present study, we tested the hypothesis that EGCG attenuates transaortic abdominal aortic constriction (TAC)‐induced ventricular hypertrophy by regulating mitogen‐activated protein kinase (MAPK) signal pathways in hypertensive rats. Four groups of rats were used: (i) a sham‐operated control group; (ii) an EGCG‐treated (50 mg/kg per day, i.p., for 21 days) sham‐operated group; (iii) a TAC group; and (iv) an EGCG‐treated TAC group. Histological analysis of whole hearts and biochemical analyses of left ventricular (LV) tissue were used to investigate the effects of EGCG.
The results showed that the LV myocyte diameter and the expression of atrial natriuretic peptide, brain natriuretic peptide and β‐myocardial heavy chain were significantly decreased in the EGCG‐treated (50 mg/kg per day, i.p.) TAC group. Levels of reactive oxygen species and malondialdehyde in the lV were significantly reduced by EGCG in the TAC group. Total superoxide dismutase, catalase and glutathione peroxidase activities were decreased in the TAC group, and this decrease was significantly restored by EGCG treatment. Phosphorylation of extracellular signal‐regulated kinase 2, p38 and c‐Jun N‐terminal kinase 1 was significantly reversed in the LV of EGCG‐treated TAC rats (40%, 53% and 52%vs TAC, respectively), accompanied by significant inhibition of nuclear factor‐κB and activator protein‐1. Transaortic abdominal aortic constriction significantly upregulated LV expression of matrix metalloproteinase‐9 from 32 ± 6 to 100 ± 12% and this increase was inhibited by EGCG treatment (from 100 ± 12 to 50 ± 15%). In addition, TAC decreased mitochondrial DNA copy number and the activity of respiratory chain complexes I (from 100 ± 7 to 68 ± 5%), III (from 100 ± 4 to 2 ± 5%) and IV (from 766 ± 2 to 100 ± 5%); this decrease was reversed by EGCG treatment to levels seen in sham‐operated rats.
In conclusion, EGCG attenuates TAC‐induced ventricular hypertrophy in hypertensive rats in part by suppression of anti‐oxidant enzymes and regulation of MAPK signals.
Contrasting demographics of tropical savanna and temperate forest eucalypts provide insight into how savannas and forests function. A case study using Corymbia clarksoniana from north‐eastern Australia
Authors: WILLIAMS PAUL R. 
Published: March 2009

AbstractEucalypts (Eucalyptus spp. and Corymbia spp.) dominate many communities across Australia, including frequently burnt tropical savannas and temperate forests, which receive less frequent but more intense fires. Understanding the demographic characteristics that allow related trees to persist in tropical savannas and temperate forest ecosystems can provide insight into how savannas and forests function, including grass–tree coexistence. This study reviews differences in critical stages in the life cycle of savanna and temperate forest eucalypts, especially in relation to fire. It adds to the limited data on tropical eucalypts, by evaluating the effect of fire regimes on the population biology of Corymbia clarksoniana, a tree that dominates some tropical savannas of north‐eastern Australia. Corymbia clarksoniana displays similar demographic characteristics to other tropical savanna species, except that seedling emergence is enhanced when seed falls onto recently burnt ground during a high rainfall period. In contrast to many temperate forest eucalypts, tropical savanna eucalypts lack canopy‐stored seed banks; time annual seed fall to coincide with the onset of predictable wet season rain; have very rare seedling emergence events, including a lack of mass germination after each fire; possess an abundant sapling bank; and every tropical eucalypt species has the ability to maintain canopy structure by epicormically resprouting after all but the most intense fires. The combination of poor seedling recruitment strategies, coupled with characteristics allowing long‐term persistence of established plants, indicate tropical savanna eucalypts function through the persistence niche rather than the regeneration niche. The high rainfall‐promoted seedling emergence of C. clarksoniana and the reduction of seedling survival and sapling growth by fire, support the predictions that grass–tree coexistence in savannas is governed by rainfall limiting tree seedling recruitment and regular fires limiting the growth of juvenile trees to the canopy.
Habitat selection by the swamp wallaby (Wallabia bicolor) in relation to diel period, food and shelter
Authors: DI STEFANO JULIAN , YORK ALAN , SWAN MATTHEW , GREENFIELD ANDREW , COULSON GRAEME 
Published: March 2009

AbstractPatterns of resource selection by animals may be influenced by sex, and often change over a 24‐h period. We used a dry sclerophyll landscape managed for commercial timber production to investigate the effects of sex and diel period on habitat selection by the swamp wallaby (Wallabia bicolor). We predicted that selection would be (i) affected by both sex and diel period; and (ii) positively related to lateral cover during the day, but to food resources at night. Non‐metric multidimentional scaling indicated that some of the available habitats differed markedly with respect to visibility (an indicator of lateral cover), fern cover, forb cover, wallaby density and a forage quality index, providing the basis for non‐random habitat selection. At the landscape scale, wallabies showed strong selection for 5‐year‐old regenerating sites, selected against 10‐year‐old regenerating sites and unharvested forest, and avoided recently harvested (3–10 months post‐harvest) sites completely. At the scale of individual home ranges, a pooled male and female sample demonstrated selection for unharvested forest over recently harvested sites during both diurnal and nocturnal periods. A separate analysis showed that both sex and diel period influenced the selection of 5‐ and 10‐year‐old sites and the surrounding unharvested forest. Using a novel approach, we demonstrated that diurnal habitat selection by both sexes was negatively correlated with visibility, representing stronger selection for areas with more lateral cover. Nocturnal selection by females was positively correlated with values of a forage quality index, but this was not the case for males. We hypothesise that the observed patterns of selection were driven by the need to find food and avoid predators, but were also affected by the different reproductive strategies of males and females. Our results demonstrate the importance of incorporating factors such as sex and diel period into analyses of habitat selection.
Impacts of hive honeybees on Tasmanian leatherwood Eucryphia lucida Labill. (Eucryphiaceae)
Authors: MALLICK STEPHEN A. , DRIESSEN MICHAEL M. 
Published: March 2009

AbstractDespite honeybees (Apis mellifera L.) occurring as a feral and commercially managed species in many parts of Australia, the effects of honeybees on native Australian ecosystems are poorly understood. We examined the impacts of honeybee apiaries on Tasmanian Leatherwood Eucryphia lucida Labill. (Eucryphiaceae) by comparing commercial apiary sites with control sites >2 km from the nearest apiary. Feral honeybees were common at control sites (73% of honeybees feral) but were scarce at apiary sites (2%), and hive honeybees appeared to be competitively displacing feral honeybees near apiaries. Visit rates by native insects appeared to be un‐affected by the increased numbers of hive honeybees near apiaries. Standing crops of nectar sugar were significantly depressed at apiary sites. Pollen was rapidly removed from flowers at apiary sites resulting in full separation of the male and female flower‐phases (flowers completely dichogamous). In contrast, at control sites, pollen tended to remain in flowers into the female phase (flowers partially dichogamous). There was no difference in the total number of pollen grains deposited on stigmas or in percentage seed set among apiary and control sites. However, fruit set was elevated at apiary sites, possibly owing to reduced autonomous (within‐flower) selfing. Our study indicated that honeybees significantly reduce floral resources (nectar and pollen) around apiaries, although any competitive effects on native insects may have been obscured by large variation in the abundance of native insects among experimental sites.
Impact of storm‐burning on Melaleuca viridiflora invasion of grasslands and grassy woodlands on Cape York Peninsula, Australia
Authors: CROWLEY GABRIEL , GARNETT STEPHEN , SHEPHARD SUSAN 
Published: March 2009

AbstractThis paper examines invasion of grasslands on Cape York Peninsula, Australia, by Melaleuca viridiflora and other woody species, and the role of storm‐burning (lighting fires after the first wet season rains) in their maintenance. Trends in disturbance features, fuel characteristics, ground layer composition, and woody plants dynamics under combinations of withholding fire and storm‐burning over a 3‐year period were measured on 19 plots in three landscape settings. Population dynamics of M. viridiflora are described in detail and 20‐year population projections based on transition matrices under different fire regimes generated. Numerous M. viridiflora suckers occurred within the grass layer, increasing each year regardless of fire regime, and were rapidly recruited to the canopy in the absence of fire. Storm‐burning had little impact on fuel, ground layer or woody plant composition, but maintained open vegetation structure by substantially reducing recruitment of M. viridiflora suckers to the sapling layer, and by reducing the above‐grass‐layer abundance of several other invasive woody species. Population projections indicated that withholding fire for 20 years could cause a sevenfold increase of M. viridiflora density on Ti‐tree flats, and that annual to triennial storm‐burning should be effective at maintaining a stable open vegetation structure. These findings argue against vegetation thickening being an inevitable consequence of climate change. We conclude that a fire regime that includes regular storm‐burning can be effective for maintaining grasslands and grassy woodlands being invaded by M. viridiflora.