bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variable maternal control of facultative egg diapause in the bushcricket Ephippiger ephippiger
Authors: Hockham Leon R. , Graves Jeff A. , Ritchie Michael G. 
Published: March 2003

Summary1. Diapause is a term used to describe an arrest in the development of insects as adults, eggs, or embryos, and allows survival during adverse environmental conditions.2. The influence of maternal age on the proportion of eggs that entered an initial facultative diapause and on fecundity and egg mortality was investigated in the bushcricket Ephippiger ephippiger.3. In the absence of variable abiotic cues such as temperature and photoperiod, most E. ephippiger females increase the proportion of their eggs that enter diapause as they age, however there are large differences among females, with a minority showing different trends. Fecundity and egg survival decline with female age and also differ among females.4. The influence of age on the incidence of diapause is likely to be an adaptive reproductive strategy, as those eggs laid later in the season are unlikely to complete egg development before the onset of winter. Females are probably hedging their bets by diversifying the rate of development among their offspring and effectively spreading development over several seasons. The low predictability of future environmental conditions might explain the heterogeneity of female reproductive strategies.
Nutritional benefits of the leaf‐mining behaviour of two grass miners: a test of the selective feeding hypothesis
Authors: Scheirs J. , De Bruyn L. , Verhagen R. 
Published: March 2003

Summary1. The selective feeding hypothesis predicts that miners prefer tissues high in nutrient content and low in chemical and structural defence content. This hypothesis was tested for two dipteran grass miners, Chromatomyia milii and C. nigra, feeding on Holcus lanatus.2. Leaf sections revealed that both miners preferred to feed on the mesophyll layer, minimised the intake of veinal tissues, and never fed on the epidermal layer. Nutritional quality analyses showed that the mesophyll had a higher nutrient content and a lower structural defence content than the epidermal and veinal tissues.3. The nutritional quality of mined leaf areas was lower than that of unmined leaf areas, suggesting that the mining larvae remove the most nutritious tissues; however this commonly used approach for studying the selective feeding hypothesis is questioned in this study.4. Larval feeding rates were higher on the mesophyll than on the veinal tissues, probably due to a higher structural defence content of the veins. Feeding rates were higher on the small veins than on the larger and more sclerified, strengthened veins.5. This study supports the selective feeding hypothesis as both species concentrated their feeding on the mesophyll, which is the most nutritious and least tough tissue within a H. lanatus leaf.
Dispersal by bagworm larvae, Metisa plana: effects of population density, larval sex, and host plant attributes
Authors: Rhainds Marc , Gries Gerhard , Ho Cheng Tuck , Chew Poh Soon 
Published: March 2003

Abstract 1. The work reported here investigated the incidence of dispersal by bagworm larvae Metisa plana (Walker) (Lepidoptera: Psychidae), a species with apterous females and winged males.2. A mark–recapture study conducted in a plantation of oil palm revealed that a significant proportion of larvae undertakes multiple episodes of ballooning, and suggested that ballooning represents a strategy for foraging both within and between hosts.3. Experiments conducted in a controlled cage environment indicated that increasing population density and defoliation of oil palm both promote dispersal by larvae.4. Neonatal larvae typically remained on the host where they emerged, indicating that pupation site of late‐instar females influences the distribution of their progeny, and suggesting a high level of genetic relatedness in localised bagworm populations.5. Density‐dependent dispersal may generate relatively uniform distributions of M. plana in plantations of oil palm, by simultaneously stabilising populations on heavily infested palms and redistributing larvae on lightly infested palms.6. The rate of ballooning was greater for female than for male larvae, possibly resulting from the sex‐specific impact of population density on reproductive success or from late‐instar females seeking suitable oviposition sites for their future progeny.
Differences in host plant selection among three Athalia sawflies feeding on crucifers in Japan
Authors: Nagasaka Koukichi , Ohsaki Naota 
Published: March 2003

Abstract 1. The ways of using host plants were compared among the three Athalia sawflies [A. japonica (Klug), A. rosae ruficornis Jakovlev, and A. infumata (Marlatt)] feeding on crucifers in Japan to determine whether host specialisation can explain the difference in their life‐history traits. The occurrence of their larvae was examined on each crucifer species in the field, and the suitability of each crucifer species for the three successive steps of host use by the sawflies was evaluated: microhabitat selection by adult females, female oviposition, and larval growth.2. There were 11 species of crucifer in the study area, and A. japonica, A. rosae, and A. infumata used nine, seven, and eight species respectively. Thus, sawfly host ranges overlapped.3. Adult females of A. japonica, A. rosae, and A. infumata preferred shady clumps of crucifers, sunny clumps of crucifers, and disturbed areas respectively.4. Unsuitable hosts for larval performance such as Brassica oleracea and Arabis plants were eliminated from the host ranges of the three sawflies.5. Once they chose microhabitats, the suitability of each host plant for female oviposition and larval growth was similar.6. Because of the divergent preferences for microhabitats, the host plants that were suitable for all the three steps were restricted to different sets of plants among the sawflies: Cardamine for A. japonica, cultivated crucifers (Raphanus and Brassica) for A. rosae, and Rorippa for A. infumata. These plants could be recognised as the respective primary host plants.7. The spatio‐temporal distributions of primary hosts were consistent with and explained the pattern of diapause and migration of each sawfly, suggesting that host specialisation caused their life‐history traits to differentiate.
Community effects of praying mantids: a meta‐analysis of the influences of species identity and experimental design
Authors: Fagan William F. , Moran Matthew D. , Rango Jessamy J. , Hurd Lawrence E. 
Published: March 2003

Abstract  1. Generalist arthropod predators are ubiquitous in terrestrial ecosystems but experimental studies have yielded little agreement as to their effects on prey assemblages. Drawing on results from a suite of experimental field studies, a meta‐analysis was conducted of the impact of praying mantids (Mantodea: Mantidae) on arthropod assemblages in order to identify predictable and unpredictable effects of these extremely generalised predators.2. Results across different experiments were synthesised using the log response ratio framework, with a focus on quantifying net mantid impacts on arthropod density across taxonomic orders and trophic levels of arthropods, paying special attention to the contribution of mantid species identity and experimental design variables, such as the use of cages, length of experiment, and manipulated mantid density.3. Calculated on a per mantid‐day basis, the net impacts of Tenodera sinensis on arthropod density were generally weaker but more predictable than the effects of Mantis religiosa. Mantids in general had weak negative effects on density for most taxa but exhibited strong negative and positive effects on some taxa. Tenodera sinensis tended to have negative effects on Homoptera, Diptera, and Hemiptera and herbivores as a group, however M. religiosa exhibited greater variation in response of different taxa that appeared to be affected more strongly by experimental design. The effects of Stagmomantis carolina tended to be negative or non‐significant.4. Experimental cages had little influence on either the sign or magnitude of net community impacts for T. sinensis, however cage experiments reversed the sign of the mean effect for two of six taxonomic orders when the experimental predator was M. religiosa. Cages also increased the variability of effect size greatly for M. religiosa but not for T. sinensis.5. It was concluded that it is possible to use log response ratios to determine general, predictable trends in a well‐studied system. Similar meta‐analyses of generalist predator effects in other systems should produce predictions of how these predators influence food webs, an important step towards defining more clearly the influences of generalist predators on community structure and dynamics.
The effects of exposure to seaweed on willingness to mate, oviposition, and longevity in seaweed flies
Authors: Dunn Derek W. , Crean Caroline S. , Gilburn André s. 
Published: March 2003

Abstract  1. Large male seaweed flies (Diptera: Coelopidae) are more likely to mate than smaller males. This is due to sexual conflict over mating, by which females physically resist male attempts to copulate. In some species, large males are simply more efficient at overpowering female resistance.2. Female reluctance to mate is likely to have evolved due to the costs of mating to females. In many dipterans, males manipulate female behaviour through seminal proteins that have evolved through sperm competition. This behavioural manipulation can be costly to females, for example forcing females to oviposit in sub‐optimal conditions and increasing their mortality.3. Previous work has failed to identify any ubiquitous costs of mating to female coelopids. The work reported here was designed to investigate the effects of exposure to oviposition sites (Fucus algae) on the reproductive behaviour of four species of coelopid. Algae deposition in nature is stochastic and females mate with multiple males in and around oviposition sites. Spermatogenesis is restricted to the pupal stage and there is last‐male sperm precedence. It was predicted that males would avoid wasting sperm and would be more willing to mate, and to remain paired with females for longer, when exposed to oviposition material compared with control males. Females were predicted to incur longevity costs of mating if mating increased their rate of oviposition, especially in the presence of algae.4. The behaviour of males of all four species concurred with the predictions; however mating did not affect female receptivity, oviposition behaviour, or longevity. Exposure to algae induced oviposition and increased female mortality in all species independently of mating and egg production. The evolutionary ecology of potential costs of mating to female coelopids are discussed in the light of these findings.
Direct gene transfer into the rat pancreas using DNA‐liposomes
Authors: Schmid  , Weidenbach  , Yamagushi  , Lührs  , Liptay  , Adler  
Published: March 2003

BackgroundPancreatic cancer represents a malignancy with very poor clinical prognosis and limited therapeutic potential. Recent developments of gene transfer technology offer new therapeutic avenues by delivering recombinant genes directly into normal or neoplastic tissue in vivo.MethodsHere we show that the LacZ marker gene, complexed to cationic liposomes, can be introduced into the pancreas by either intraductal or intra‐arterial injection. Expression of the β‐galactosidase gene product was monitored by polymerase chain reaction and histochemistry.ResultsUp to 28 days after in vivo gene transfer, β‐galactosidase activity could be demonstrated in the pancreas. Intraductal application induced gene expression in lining duct cells preferentially. Twenty‐four hours after intraductal injection of liposomes, a dose‐dependent, transient increase in serum amylase levels was detected. Nevertheless, no histological signs of pancreatitis were evident. Intra‐arterial injection resulted in β‐galactosidase expression in endothelial cells of intrapancreatic arteries, as well as in the spleen, lymph nodes and liver, but not in ductal cells of the pancreas. Only occasionally were acinar cells positive for blue staining by either type of treatment.ConclusionThese experiments demonstrate that in vivo gene transfer into the pancreas is feasible using DNA–liposome complexes. Furthermore, the route of administration largely determines cell type specificity and side‐effects. This technique might have an impact for the development of gene therapy strategies for pancreatic diseases.
Pneumocystis carinii induces interleukin 6 production by an alveolar epithelial cell line
Authors: Pottratz  , Reese  , Sheldon  
Published: March 2003

Background Pneumocystis carinii (PC) infection often results in severe pneumonia in immunocompromised patients. Attachment of PC organisms to alveolar epithelial cells is a hallmark of PC pneumonia; however, few studies have investigated the response of alveolar epithelial cells to PC infection.MethodsInterleukin 6 (IL‐6) is a multifunctional cytokine that is produced by alveolar epithelial cells in response to a variety of stimuli. Our investigation was undertaken to determine whether PC organisms induce production of IL‐6 by alveolar epithelial cells and to determine the effect of IL‐6 on PC attachment.ResultsIncubation of the human alveolar epithelial cell line, A549, with PC organisms resulted in a significant increase in IL‐6 secreted into the cell culture media. Time‐course studies showed that IL‐6 production was detected as soon as 2 h after addition of PC and continued up to 48 h of exposure. Further studies demonstrated that preincubation of A549 cells with IL‐6 resulted in a concentration‐dependent increase in both A549 cell production of fibronectin and PC attachment.ConclusionThus, PC attachment to an alveolar epithelial cell line results in epithelial cell production of IL‐6, which can act to further increase PC attachment. This may provide an important mechanism whereby PC organisms directly affect the host response to PC infection.
Use of cholesterol precursors to assess changes in cholesterol synthesis under non‐steady‐state conditions
Authors: Pfohl  , Naoumova  , Kim  , Thompson  
Published: March 2003

BackgroundQuantification of plasma levels of an early and late intermediate on the cholesterol pathway, mevalonic acid (MVA) and lathosterol respectively, provides a useful method of estimating cholesterol synthesis in humans. The aim of this study was to assess further their roles as indices of cholesterol synthesis under non‐steady‐state conditions.MethodsThe short‐term effects of pharmacological inhibition of 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase on both variables were determined in four normolipidaemic subjects during and after treatment with simvastatin 20 mg daily. Plasma MVA was measured using gas chromatography–mass spectrometry, and lathosterol using gas chromatography.ResultsA single dose of 20 mg of simvastatin decreased plasma MVA after 2 h and decreased the lathosterol–cholesterol (L/C) ratio after 4 h. Treatment with simvastatin 20 mg daily for 9 days decreased both variables by approximately 50%, the nadir of plasma MVA occurring on the second day and of the L/C ratio on the fifth day, and resulted in a 39% reduction in low‐density lipoprotein (LDL)‐cholesterol. After discontinuing simvastatin, there were rebounds in plasma MVA and the L/C ratio to above basal levels but not in LDL cholesterol or apolipoprotein B (apoB), the latter continuing to decrease for a further 2 days.ConclusionThese results suggest that simvastatin rapidly down‐regulates cholesterol synthesis, which is then up‐regulated when the drug is withdrawn.
The association of type II pneumocytes and endothelial permeability with the pulmonary custocyte system in experimental acute pancreatitis
Authors: Wang  , Börjesson  , Sun  , Wallèn  , Deng  , Zhang  , Hallberg  , Andersson  
Published: March 2003

BackgroundPancreatitis‐associated pulmonary injury is still associated with substantial mortality, especially when seen as a part of the multiple organ dysfunction syndrome.MethodsThe present study aimed at evaluating alterations in type II pneumocytes and the potential relationship with the development of pulmonary injury after acute haemorrhagic pancreatitis induced by an intraductal infusion of 5% sodium taurodeoxycholate in the rat.ResultsThe results demonstrated that definite alterations in type II pneumocytes were noted 12 and 24 h after induction of pancreatitis, characterized by an increase in the number of vocalized lamellae, the exposed area of type II pneumocytes to alveolar airspace, cellular separation and apoptosis without alterations in cellular membrane integrity. Dysfunction of the pulmonary endothelial barrier was evidenced by an increase in pulmonary albumin flux and the leakage index as well as the migration of lanthanum probes from capillaries to interstitial tissues. The levels of tumour necrosis factor (TNF) in bronchoalveolar lavage fluid significantly increased during the initial phase (3 and 6 h) after pancreatitis. The phagocytic activity of the pulmonary custocyte system increased 3 and 12 h after induction of pancreatitis.ConclusionThus, pulmonary endothelial barrier dysfunction, an activated custocyte system, and initial release of TNF seems to be involved in the pathogenesis of pancreatitis‐associated type II pneumocyte compromise.
Association of high plasma antioxidant capacity with new lesion formation in carotid atherosclerosis: a prospective study
Authors: Reinisch  , Kiechl  , Mayr  , Schratzberger  , Dunzendorfer  , Kähler  , Buratti  , Willeit  , Wiedermann  
Published: March 2003

BackgroundIn atherosclerosis, both reductions and elevations in plasma levels of antioxidants have been reported. This study investigated total antioxidant capacity of plasma from subjects with atherosclerotic disease.Materials and methodsThe study population consisted of 48 men with or without carotid atherosclerosis. At baseline (1990) carotid arteries were evaluated by duplex sonography and plasma samples were obtained for testing antioxidant capacity by two different test systems. One assay system used neutrophils from healthy volunteers as a source of oxygen free radicals activating the non‐fluorescent dichlorofluorescin diacetate in the presence of antioxidant containing plasma from study subjects. In the other test system, total plasma antioxidants were detected colorimetrically by using 2,2′‐azino‐di‐(3‐ethylbenzthiazoline sulphonate), metmyoglobin and superoxide in the presence of plasma. Carotid arteries were re‐evaluated for the development of new plaques 5 years later (1995).ResultsIncreased baseline total antioxidant capacity of plasma was significantly associated with the development of new atherosclerotic lesions during a period of 5 years.ConclusionsEndogenous antioxidant capacity of plasma is increased in patients with active atherosclerotic disease. As scavenging of oxygen free radicals is thought to protect from atherogenesis, elevated antioxidative capacity may represent an adaptive mechanism.
Impaired glycolysis and protein catabolism induced by acid in L6 rat muscle cells
Authors: Bevington  , Brown  , Pratt  , Messer  , Walls  
Published: March 2003

BackgroundIn skeletal muscle, metabolic acidosis stimulates protein degradation and oxidation of branched‐chain amino acids. This could occur to compensate for impairment of glucose utilization induced by acid.MethodsTo test this hypothesis, glycolysis and protein degradation (release of [14C]‐phenylalanine) were measured in L6 skeletal muscle cells cultured in Eagle's minimum essential medium at pH 7.1 or 7.5 for up to 3 days.ResultsNo marked changes in total DNA or in cell viability were detected, nor was there any significant effect on intracellular pH or the water content of the cells (which is thought to be a key regulator of protein turnover, especially in liver). In spite of this, acid stimulated protein degradation, induced net protein loss from the cultures, inhibited glucose uptake and glycolysis (lactate output) and was associated with increased [1‐14C]‐leucine oxidation. Effects on protein degradation and glycolysis were gradual, reaching a maximum after 20–30 h. To investigate whether glycolytic flux itself can influence protein degradation, increased glycolysis was simulated by adding glucose (20 mmol L−1) or pyruvate (1 mmol L−1) to the medium. At pH 7.1, neither addition had any effect on protein degradation.ConclusionAlthough acid‐induced protein wasting is associated with impaired glycolysis, no obligatory coupling exists between glycolytic flux and protein degradation.
Gestational hypertension plasma and human umbilical vein endothelial cells: an in vitro study
Authors: Cester  , Salvolini  , Rabini  , Tranquilli  , Zolese  , Mazzanti  
Published: March 2003

BackgroundThe action of plasma from women affected by gestational hypertension (GH) on nitric oxide synthase (NOS) activity in cultured human umbilical vein endothelial cells (HUVECs) was evaluated in the present study, together with the effect on cytosolic calcium, on Na+, K+‐ATPase activity and on membrane fluidity.MethodsAt 80% confluence, cultured HUVECs were incubated for 3 h at 37°C with fresh culture medium (control samples) or with 20% (v/v) plasma (from five healthy non‐pregnant women, five healthy pregnant women and five pregnant women affected by GH).ResultsAfter incubation with GH plasma, we observed a significant reduction in NOS activity, intracellular calcium concentrations and Na+, K+‐ATPase activity.ConclusionsThe present work gives further support to the hypothesis that a circulating factor in gestational hypertension, possibly produced by the fetoplacental unit, causes dysfunction of the vascular endothelial cells and NO reduction, resulting in a loss of vascular refractoriness to vasoactive agents.
Induction of rat uncoupling protein‐2 gene treated with tumour necrosis factor alpha in vivo
Authors: Masaki  , Yoshimatsu  , Kakuma  , Chiba  , Hidaka  , Tajima  , Kurokawa  , Sakata  
Published: March 2003

BackgroundThe cytokine tumour necrosis factor (TNF) α has been reported to induce metabolic abnormalities such as anorexia and thermogenesis. To investigate functional modulators of uncoupling protein‐2 (UCP2) gene expression, we examined the effects of TNF‐α on UCP2 mRNA expression in rats.MethodsMature male Wistar King A (WKA) rats at 10–11 weeks of age were treated with recombinant human TNF‐α at a dose of 0.6 nmol 100 g−1 body weight by intraperitoneal administration.ResultsTNF‐α treatment induced an increase in UCP2 mRNA expression in broadly distributed tissues including brown adipose tissue (BAT), white adipose tissue (WAT) and skeletal muscle, and an elevation of ob gene mRNA expression in WAT. After the TNF‐α treatment, an increase in plasma leptin concentration occurred in an ob gene‐dependent manner, accompanied by an anorectic effect.ConclusionThe present results provide evidence for a new regulatory loop involving TNF‐α and UCP2, and add novel insights into the regulatory mechanisms of energy homeostasis.