bluuebunny/crossref_metadata_2025 huggingface dataset:
Divergence in the calling songs between sympatric and allopatric populations of the southern wood cricket Gryllus fultoni (Orthoptera: Gryllidae)
Authors: Jang Y. , Gerhardt H. C.
Published: October 2005

In the eastern United States the wood cricket Gryllus fultoni (Orthoptera: Gryllidae) occurs in sympatry with G. vernalis in an area between eastern Kansas and west of the Appalachian Mountains. Calling songs were recorded from 13 sympatric and allopatric localities. Both field and laboratory recordings showed that chirp rate (CR) and pulse rate (PR) overlapped extensively between allopatric populations of G. fultoni and sympatric populations of G. vernalis; by contrast, there was little or no overlap in these variables between sympatric populations of these two species. Divergence in PR and CR between the two species was thus greater in areas of sympatry than in areas of allopatry. Our field and laboratory studies of G. fultoni calling songs thus demonstrate the pattern expected of character displacement and support the genetic assumptions of this hypothesis. Other possible explanations for the sympatric divergence such as ecological character displacement and clinal variation are discussed.
Predator-induced phenotypic plasticity in tadpoles: extension or innovation?
Authors: Kraft P. G. , Franklin C. E. , Blows M. W.
Published: October 2005

Phenotypic plasticity, the ability of a trait to change as a function of the environment, is central to many ideas in evolutionary biology. A special case of phenotypic plasticity observed in many organisms is mediated by their natural predators. Here, we used a predator–prey system of dragonfly larvae and tadpoles to determine if predator-mediated phenotypic plasticity provides a novel way of surviving in the presence of predators (an innovation) or if it represents a simple extension of the way noninduced tadpoles survive predation. Tadpoles of Limnodynastes peronii were raised in the presence and absence of predation, which then entered a survival experiment. Induced morphological traits, primarily tail height and tail muscle height, were found to be under selection, indicating that predator-mediated phenotypic plasticity may be adaptive. Although predator-induced animals survived better, the multivariate linear selection gradients were similar between the two tadpole groups, suggesting that predator-mediated phenotypic plasticity is an extension of existing survival strategies. In addition, nonlinear selection gradients indicated a cost of predator-induced plasticity that may limit the ability of phenotypic plasticity to enhance survival in the presence of predators.
Altitudinal patterns for latitudinally varying traits and polymorphic markers in Drosophila melanogaster from eastern Australia
Authors: Collinge J. E. , Hoffmann A. A. , Mckechnie S. W.
Published: October 2005

Altitudinal changes in traits and genetic markers can complement the studies on latitudinal patterns and provide evidence of natural selection because of climatic factors. In Drosophila melanogaster, latitudinal variation is well known but altitudinal patterns have rarely been investigated. Here, we examine five traits and five genetic markers on chromosome 3R in D. melanogaster collected at high and low altitudes from five latitudes along the eastern coast of Australia. Significant altitudinal differentiation was observed for cold tolerance, development time, ovariole number in unmated females, and the microsatellite marker DMU25686. Differences tended to match latitudinal patterns, in that trait values at high altitudes were also found at high latitudes, suggesting that factors linked to temperature are likely selective agents. Cold tolerance was closely associated with average temperature and other climatic factors, but no significant associations were detected for the other traits. Genes around DMU25686 represent good candidates for climatic adaptation.
Combined influence of maternal and paternal quality on sex allocation in red-capped robins
Authors: Dowling D. K. , Mulder R. A.
Published: October 2005

Sex allocation theory predicts females will adaptively manipulate sex ratios to maximize their progeny's reproductive value. Recently, the generality of biased sex allocation in birds has been questioned by meta-analytic reviews, which demonstrate that many previously reported significant results may simply reflect sampling error. Here, we utilize a robust sample size and powerful statistical approach to determine whether parental quality is correlated with biased sex allocation in red-capped robins. Indices of maternal quality (including interactive effects of age and condition) were strongly related to sex allocation. These relationships were in the predicted directions, with larger effect sizes than those of previous studies in this field. There were also paternal correlates, involving age and the source of paternity. We propose that biased sex allocation occurs in this species, and is maintained by differing production costs of each sex and genetic benefits to females of producing sons when fertilized by high-quality males.
α‐Ketoglutarate (AKG) absorption from pig intestine and plasma pharmacokinetics
Authors: Dąbek M. , Kruszewska D. , Filip R. , Hotowy A , Pierzynowski Ł. , Wojtasz‐Pająk A. , Szymanczyk S. , Valverde Piedra J. L. , Werpachowska E. , Pierzynowski S. G.
Published: October 2005

To study the absorption, metabolism and kinetics, the AKG (in different concentrations) was administered intravenously, intra‐portally, orally and directly into the ileum or duodenum of pigs, chronically fitted with portal and jugular catheters and T‐shaped cannula at the duodenum and ileum. Additionally, this study was conducted to determine the influence of low pH, Fe2+or/and SOon AKG gut absorption and conversely FeSO4and FeSO4/AKG on Fe2+gut absorption. It is concluded that AKG was significantly better absorbed from the upper small intestine than from the distal sections. Furthermore, low pH, Fe2+and/or SOions enhanced AKG absorption. The AKG administered to the portal vein was rapidly eliminated from the blood (half‐life less than 5 min). The short lifetime for AKG is probably dependent on quick metabolism in the enteorcyetes and liver. However, the prolonged half‐life can be related to its low AKG blood concentration. The Fe2+concentrations in blood increased after FeSO4and FeSO4/AKG duodenal infusion. The implication of above observations is important for practical application of the AKG in animal and human nutrition as well in medicine.
Genomic constitution of Festulolium cultivars released in the Czech Republic
Authors: Kopecky D. , Lukaszewski A. J. , Doležel J.
Published: October 2005

Genomic in situ hybridization (GISH) was used to characterize the chromosome constitutions of individual plants from a set of tetraploid and hexaploid cultivars of Festulolium developed and released in the Czech Republic from hybrids of Lolium multiflorum with Festuca pratensis and F. arundinacea. A simplified GISH protocol readily discriminated parental genomes in the hybrids and facilitated the screening of large numbers of plants per accession. The contribution of parental genomes in the cultivars tested ranged from predominance of chromatin from one of the parents to a more balanced contribution from both parents. However, in none of the cultivars were equal proportions of chromatin from both parents present. The parental contribution to the hybrids was both in the form of complete chromosomes or as chromosome translocations. In hexaploid cultivars from (L. multiflorum × F. arundinacea) × F. arundinacea hybrids the average numbers of complete L. multiflorum chromosomes ranged from 4.95 to 7.5 and the numbers of translocations from 6.33 to 10.21. Two tetraploid cultivars from (L. multiflorum × F. arundinacea) × L. multiflorum hybrids showed a strong prevalence of L. multiflorum chromatin and intergeneric translocations were rare. In the tetraploid cultivar ‘Perun’ of the L. multiflorum × F. pratensis hybrid there were 11.7 chromosomes of L. multiflorum and 14.7 recombined chromosomes on average. Reasons for the domination of one of the parental genomes in hybrid cultivars are not clear and are only partially explained by breeding history. Recombination rates of individual genomes in hybrids involving F. arundinacea were evaluated in double hybridization experiments. The results indicated a strong affinity of the L. multiflorum genome for the F. pratensis genome present in F. arundinacea and little affinity for the F. glaucescens genome. This suggests that introgressions from F. arundinacea into L. multiflorum are primarily limited to the F. pratensis genome which can be more readily accessed in L. multiflorum × F. pratensis hybrids.
Potential of Nicotiana glauca (Grah.) as a source of resistance to black root rot Thielaviopsis basicola (Berk. and Broome) Ferr. in tobacco improvement
Authors: Trojak‐Goluch A. , Berbeć A.
Published: October 2005

Nicotiana glauca, a wild relative of Nicotiana tabacum, is an attractive potential source of black root rot (Thielaviopsis basicola)‐resistant germplasm. Moreover, it shows a resistance or tolerance to PVY, TEV, anthracnose and powdery mildew. In this study its potential as a source of resistance to black root rot caused by Th. basicola was investigated. Nicotiana glauca GG (2n = 2x = 24) was crossed as male with two N. tabacum TT (2n = 4x = 48) flue‐cured cultivars: ‘BY103’ and ‘K 326’, both of which are susceptible to black root rot. Amphihaploid F1 TG (2n = 3x = 36), amphidiploid TTGG (2n = 6x = 72) and sesquidiploid TTG (2n = 5x = 60) hybrids were obtained. The resultant sesquidiploid hybrids were used as maternal components in backcrossing to N. tabacum and a segregating post‐sesquidiploid TTg (2n = 5x = 52–54) offspring was obtained. Amphihaploids exhibited a level of resistance to black root rot characteristic of N. glauca. The expression of resistance varied in the sesquidiploid generation, possibly reflecting cytological instabilities in that progeny. A wide variation in response to black root rot was found for post‐sesquidiploids a clear reflection of extensive chromosome segregation in that hybrid generation.
Genetic diversity of Phaseolus vulgaris L. and P. coccineus L. landraces in central Italy
Authors: Sicard D. , Nanni L. , Porfiri O. , Bulfon D. , Papa R.
Published: October 2005

The genetic diversity of 66 Phaseolus genotypes was investigated, which included 14 local varieties of Phaseolus vulgaris and nine local varieties of P. coccineus, collected in Marche, central Italy. Their genetic diversity was assessed using three types of molecular marker: inter simple sequence repeats (ISSRs), nuclear gene‐tagged simple sequence repeats (SSRs) and chloroplast simple sequence repeats (CpSSRs). Phaseolus vulgaris shows a higher genetic diversity than P. coccineus for the SSRs and CpSSRs, but not for the putative neutral ISSR markers. These data suggest that selection by farmers and adaptation to heterogeneous environments has maintained the diversity in landraces of the common bean. Comparing genetic diversity in Marche with that of the American controls reveals that 71% of the local P. vulgaris varieties in Marche are of Andean origin. The two gene pools of the common bean can be found on the same farm, and there is some evidence of past hybridization events between these two gene pools.
Generation and characterization of a high molecular weight glutenin 1Bx14‐deficient mutant in common wheat
Authors: Zhu Y. F. , Li Y. W. , Chen Y. , Li H. , Liang H. , Yue S. J. , Zhang A. M. , Zhang X. Q. , Wang D. W. , Jia X.
Published: October 2005

Significant progress has been made in understanding the structure of high molecular weight (HMW) glutenin subunits and their role in determining the end use quality of wheat grains. However, few reports have dealt with the development and characterization of knock out mutants for HMW glutenin subunit genes. Here, the molecular analysis of MB14, a mutant derived from an elite Chinese wheat variety Xiaoyan 54 through chemical mutagenesis is described. SDS‐PAGE and Western blot experiments revealed that, in the seeds of homozygous MB14 plants, the expression of the 1Bx14 subunit was specifically blocked whereas the remaining four subunits (1Ax1, 1By15, 1Dx2, 1Dy12) accumulated to levels comparable to those in the wild type plants. The 5′‐flanking region and the open reading frame (ORF) of the mutant 1Bx14 allele were amplified and compared to the corresponding regions of wild type 1Bx14. The nucleotide sequences of the 5′‐flanking regions from the mutant and wild type 1Bx14 alleles were identical. However, the ORF of the mutant allele differed from that of the wild type 1Bx14 by three point substitutions, one of which resulted in a premature stop codon in the mutant ORF. Interestingly, the mutant 1Bx14 allele was still transcribed in the developing seeds, but no truncated translation product could be detected by Western blot analysis. Potential application of the 1Bx14 knock out mutant in studying the biological function of 1Bx14 and its contribution to the end use quality control in hexaploid wheat is discussed.
Adaptation and stability analysis of sweet potato varieties for low‐input systems in Uganda
Authors: Abidin P. E. , van Eeuwijk F. A. , Stam P. , Struik P. C. , Malosetti M. , Mwanga R. O. M. , Odongo B. , Hermann M. , Carey E. E.
Published: October 2005

Sixteen sweet potato varieties were evaluated for fresh storage root yield in 20 trials during 2000–2001 for three seasons in four locations in Uganda. Of the 16 varieties, 11 were developed by farmers and five by a central breeding programme. The behaviour of the varieties was quantified in terms of wide adaptation (genotypic mean across trials), specific adaptation (genotypic predictions for specific locations) and stability (Shukla stability variance). With respect to all three aspects of yield behaviour, farmer varieties performed on average better than the official varieties. The results illustrate the potential that farmer varieties can have in the improvement of sweet potato in Uganda and other regions where high diversity of sweet potato landraces exists.
Recruitment of the Sonic hedgehog signalling cascade in electroconvulsive seizure‐mediated regulation of adult rat hippocampal neurogenesis
Authors: Banerjee Sunayana B. , Rajendran Rajeev , Dias Brian G. , Ladiwala Uma , Tole Shubha , Vaidya Vidita A.
Published: October 2005

Electroconvulsive seizure (ECS) induces structural remodelling in the adult mammalian brain, including an increase in adult hippocampal neurogenesis. The molecular mechanisms that underlie this increase in the proliferation of adult hippocampal progenitors are at present not well understood. We hypothesized that ECS may recruit the Sonic hedgehog (Shh) pathway to mediate its effects on adult hippocampal neurogenesis, as Shh is known to enhance the proliferation of neuronal progenitors and is expressed in the adult basal forebrain, a region that sends robust projections to the hippocampus. Here we demonstrate that the ECS‐induced increase in proliferation of adult hippocampal progenitors was completely blocked in animals treated with cyclopamine, a pharmacological inhibitor of Shh signalling. Our results suggest that both acute and chronic ECS enhance Shh signalling in the adult hippocampus, as we observed a robust upregulation of Patched (Ptc) mRNA, a component of the Shh receptor complex and a downstream transcriptional target of Shh signalling. This increase was rapid and restricted to the dentate gyrus, where the adult hippocampal progenitors reside. In addition, both acute and chronic ECS decreased Smoothened (Smo) mRNA, the other component of the Shh receptor complex, selectively within the dentate gyrus. However, ECS did not appear to influence Shh expression within the basal forebrain, the site from which it has been suggested to be anterogradely transported to the hippocampus. Together, our findings demonstrate that ECS regulates the Shh signalling cascade and indicate that the Shh pathway may be an important mechanism through which ECS enhances adult hippocampal neurogenesis.
Intrinsic subthreshold oscillations of the membrane potential in pyramidal neurons of the olfactory amygdala
Authors: Sanhueza Magdalena , Bacigalupo Juan
Published: October 2005

The amygdala complex is a heterogeneous group of temporal lobe brain structures involved in the processing of biologically significant sensory stimuli and in the generation of appropriate responses to them. The amygdala has also been implicated in certain forms of emotional learning and memory. While much progress has been made in understanding neural processing in the basolateral subgroup of the amygdala, physiological studies in the cortical regions of the complex, also known as olfactory amygdala, are missing. Using a rat brain slice preparation, we conducted whole‐cell recordings on pyramidal neurons of the periamygdaloid cortex and the anterior cortical nucleus, two structures receiving direct connections from the olfactory bulb. Upon depolarization by current injection through the recording electrode, a fraction of periamygdaloid cortex and most anterior cortical nucleus layer II pyramidal neurons displayed an intermittent discharge pattern, where clusters of action potentials were interspersed by periods of membrane potential subthreshold oscillations. Oscillations frequency increased with membrane potential and correlated linearly with the cluster spiking frequency. Frequency ranged from 3 to 20 Hz, considering different cells and membrane potential values (up to approximately 30 mV above resting potentials of typically approximately −70 mV). Subthreshold oscillations were preserved after pharmacological inhibition of fast excitatory and inhibitory synaptic transmission, but were abolished by application of the sodium channel blocker tetrodotoxin. We conclude that pyramidal neurons of the olfactory cortical amygdala display intrinsically generated voltage‐dependent membrane potential rhythmic fluctuations in the theta‐low beta range, requiring the activation of a sodium conductance.
Hyposmolarity evokes norepinephrine efflux from synaptosomes by a depolarization‐ and Ca2+‐dependent exocytotic mechanism
Authors: Tuz K. , Pasantes‐Morales H.
Published: October 2005

Osmolarity reduction (20%) elicited 3H‐norepinephrine (NE) efflux from rat cortical synaptosomes. The hyposmotic NE release resulted from the following events: (i) a Na+‐dependent and La3+‐, Gd3+‐ and ruthenium red‐sensitive depolarization; (ii) a cytosolic Ca2+ ([Ca2+]i) rise with contributions from external Ca2+ influx and internal Ca2+ release, probably through the mitochondrial Na+–Ca2+ exchanger; and (iii) activation of a [Ca2+]i‐evoked, tetanus toxin (TeTX)‐sensitive, PKC‐modulated NE efflux mechanism. This sequence was established from results showing a drop in the hyposmotic [Ca2+]i rise by preventing depolarization with La3+, and by the inhibitory effects of Ca2+‐free medium (EGTA; 50%), CGP37157 (the mitochondrial Na+–Ca2+ exchanger blocker; 48%), EGTA + CGP37157 or by EGTA‐AM (> 95% in both cases). In close correspondence with these effects, NE efflux was 92% decreased by Na+ omission, 75% by La3+, 47% by EGTA, 50% by CGP37157, 90% by EGTA + CGP37157 and 88% by EGTA‐AM. PKC influenced the intracellular Ca2+ release and, mainly through this action, modulated NE efflux. TeTX suppressed NE efflux. The K+‐stimulated NE release, studied in parallel, was unaffected by Na+ omission, or by La3+, Gd3+ or ruthenium red. It was fully dependent on external Ca2+, insensitive to CGP37157 and abolished by TeTX. These results suggest that the hyposmotic events, although different from the K+‐evoked depolarization and [Ca2+]i rise mechanisms, are able to trigger a depolarization‐dependent, Ca2+‐dependent and TeTX‐sensitive mechanism for neurotransmitter release.
A synthetic NCAM‐derived peptide, FGL, protects hippocampal neurons from ischemic insult both in vitro and in vivo
Authors: Skibo Galina G. , Lushnikova Iryna V. , Voronin Kyrill Y. , Dmitrieva Oksana , Novikova Tatiana , Klementiev Boris , Vaudano Elisabetta , Berezin Vladimir A. , Bock Elisabeth
Published: October 2005

There is a major unmet need for development of innovative strategies for neuroprotection against ischemic brain injury. Here we show that FGL, a neural cell adhesion molecule (NCAM)‐derived peptide binding to and inducing phosphorylation of the fibroblast growth factor receptor (FGFR), acts neuroprotectively after an ischemic insult both in vitro and in vivo. The neuroprotective activity of FGL was tested in vitro on dissociated rat hippocampal neurons and hippocampal slice cultures, using a protocol of oxygen–glucose deprivation (OGD). FGL protected hippocampal neurons from damage and maintained or restored their metabolic and presynaptic activity, both if employed as a pretreatment alone to OGD, and if only applied after the insult. In vivo 24 h pretreatment with a single suboccipital injection of FGL significantly protected hippocampal CA1 neurons from death in a transient global ischemia model in the gerbil. We conclude that FGL promotes neuronal survival after ischemic brain injury.
Neurovascular coupling investigated with two‐dimensional optical imaging spectroscopy in rat whisker barrel cortex
Authors: Berwick J. , Johnston D. , Jones M. , Martindale J. , Redgrave P. , McLoughlin N. , Schiessl I. , Mayhew J. E. W.
Published: October 2005

Optical imaging slit spectroscopy is a powerful method for estimating quantitative changes in cerebral haemodynamics, such as deoxyhaemoglobin, oxyhaemoglobin and blood volume (Hbr, HbO2 and Hbt, respectively). Its disadvantage is that there is a large loss of spatial data as one image dimension is used to encode spectral wavelength information. Single wavelength optical imaging, on the other hand, produces high‐resolution spatiotemporal maps of brain activity, but yields only indirect measures of Hbr, HbO2 and Hbt. In this study we perform two‐dimensional optical imaging spectroscopy (2D‐OIS) in rat barrel cortex during contralateral whisker stimulation to obtain two‐dimensional maps over time of Hbr, HbO2 and Hbt. The 2D‐OIS was performed by illuminating the cortex with four wavelengths of light (575, 559, 495 and 587 nm), which were presented sequentially at a high frame rate (32 Hz). The contralateral whisker pad was stimulated using two different durations: 1 and 16 s (5 Hz, 1.2 mA). Control experiments used a hypercapnic (5% CO2) challenge to manipulate baseline blood flow and volume in the absence of corresponding neural activation. The 2D‐OIS method allowed separation of artery, vein and parenchyma regions. The magnitude of the haemodynamic response elicited varied considerably between different vascular compartments; the largest responses in Hbt were in the arteries and the smallest in the veins. Phase lags in the HbO2 response between arteries and veins suggest that a process of upstream signalling maybe responsible for dilating the arteries. There was also a consistent increase in Hbr from arterial regions after whisker stimulation.
A similar impairment in CA3 mossy fibre LTP in the R6/2 mouse model of Huntington's disease and in the complexin II knockout mouse
Authors: Gibson Helen E. , Reim Kerstin , Brose Nils , Morton A. Jennifer , Jones Susan
Published: October 2005

Complexin II is reduced in Huntington's disease (HD) patients and in the R6/2 mouse model of HD. Mice lacking complexin II (Cplx2–/– mice) show selective cognitive deficits that reflect those seen in R6/2 mice. To determine whether or not there is a common mechanism that might underlie the cognitive deficits, long‐term potentiation (LTP) was examined in the CA3 region of hippocampal slices from R6/2 mice and Cplx2–/– mice. While associational/commissural (A/C) LTP was not significantly different, mossy fibre (MF) LTP was significantly reduced in slices from R6/2 mice and Cplx2–/– mice compared with wild‐type (WT) and Cplx2+/+ control mice. MF field excitatory postsynaptic potentials (fEPSPs) in response to paired stimuli were not significantly different between control mice and R6/2 or Cplx2–/– mice, suggesting that MF basal glutamate release is unaffected. Forskolin (30 µm) caused an increase in glutamate release at MF synapses in slices from R6/2 mice and from Cplx2–/– mice that was not significantly different from that seen in control mice, indicating that the capacity for increased glutamate release is not diminished. Thus, R6/2 mice and Cplx2–/– mice have a common selective impairment of MF LTP in the CA3 region. Together, these data suggest that complexin II is required for MF LTP, and that depletion of complexin II causes a selective impairment in MF LTP in the CA3 region. This impairment in MF LTP could contribute to spatial learning deficits observed in R6/2 and Cplx2–/– mice.
Thyroid hormone‐induced morphological differentiation and maturation of astrocytes involves activation of protein kinase A and ERK signalling pathway
Authors: Ghosh Mausam , Gharami Kusumika , Paul Surojit , Das Sumantra
Published: October 2005

Thyroid hormone (TH) has a profound effect on astrocyte differentiation and maturation. Astrocytes cultured under TH‐deficient conditions fail to transform from flat polygonal morphology to mature, process‐bearing, stellate cells. Supplementation of physiological concentrations of TH initiate gradual transformation of the cells and the process takes ≈ 48 h to complete. The signal transduction pathways associated with TH‐mediated maturation of astrocytes have been investigated. TH treatment caused an initial activation of protein kinase A (PKA), with a peak activity at 2 h which fell back to basal level there after. Although there was no visible change in morphology of the cells during the observed activation of PKA, it was sufficient to drive the process of transformation to completion, suggesting the involvement of downstream regulators of PKA. PKA inhibitors as well as the MEK inhibitor PD098059 attenuated the TH‐induced morphological transformation. Further studies showed that TH treatment resulted in a biphasic response on the cellular phospho‐MAP kinase (p‐MAPK or p‐ERK) level: an initial decline in the p‐ERK level followed by an induction at 18–24 h, both of which could be blocked by a PKA inhibitor. Such sustained activation of p‐ERK levels by TH at this later stage coincided with initiation of morphological differentiation of the astrocytes and appeared to be critical for the transformation of astrocytes. The nitric oxide synthase (NOS) inhibitor 7‐NI inhibited this induction of p‐ERK activity. Moreover, the induction was accompanied by a parallel increase in phospho‐CREB activity which, however, persisted at the end of the transformation of the astroglial cells.
Recruitment of local excitatory circuits in the superior colliculus following deafferentation and the regeneration of retinocollicular inputs
Authors: Turner J. P. , Sauvé Y. , Varela‐Rodriguez C. , Lund R. D. , Salt T. E.
Published: October 2005

The local synaptic connectivity in the superficial gray layer of the superior colliculus (SC) was assessed following retinal ganglion cell axonal regeneration through a peripheral nerve graft into the SC of Lister Hooded rats, using in vitro brain slice techniques. Repair was effected between the ipsilateral eye and SC, following bilateral lesion of optic nerves and ablation of ipsilateral occipital cortex. Deafferentation surgery alone resulted in a complete loss of synaptic potentials of extrinsic origin, once both retinal and cortical inputs were removed. Stimulation of graft insertion sites elicited synaptic responses comprising monosynaptic and network‐mediated depolarising events. This activity, together with similar spontaneous bursts of depolarising events and action potential firing, was generated by the activation of non‐N‐methyl‐d‐aspartate glutamate receptors. This behaviour may reflect the development of a local recurrent synaptic connectivity following the repair surgery, as both evoked and spontaneous responses developed into large long‐lasting bursts of excitatory activity when inhibition mediated by GABA receptors was blocked. These results suggest that the ultrastructural changes in the superficial layers of the SC resulting from deafferentation are reflected functionally at the synaptic level in the target structure even after repair. Such changes are likely to compromise the ability of the target structure to function normally during information processing. Therefore, although axons regenerating along peripheral nerve grafts can make functional synaptic connections, their efficacy in activating the target structure will probably be compromised by local changes in synaptic connectivity.
Memory strengthening by a real‐life episode during reconsolidation: an outcome of water deprivation via brain angiotensin II
Authors: Frenkel Lia , Maldonado Héctor , Delorenzi Alejandro
Published: October 2005

A considerable body of evidence reveals that consolidated memories, recalled by a reminder, enter into a new vulnerability phase during which they are susceptible to disruption again. Consistently, reconsolidation was shown by the amnesic effects induced by administration of consolidation blockers after memory labilization. To shed light on the functional value of reconsolidation, we explored whether an endogenous process activated during a concurrent real‐life experience improved this memory phase. Reconsolidation of long‐term contextual memory has been well documented in the crabChasmagnathus. Previously we showed that angiotensin II facilitates memory consolidation. Moreover, water deprivation increases brain angiotensin and improves memory consolidation and retrieval through angiotensin II receptors. Here, we tested whether concurrent water deprivation improves reconsolidation via endogenous angiotensin and therefore strengthens memory. We show that memory reconsolidation, induced by training context re‐exposure, is facilitated by a concurrent episode of water deprivation, which induces a raise in endogenous brain angiotensin II. Positive modulation is expressed by full memory retention, despite a weak training, 24 or 72 but not 4 h after memory reactivation. This is the first evidence that memory can be positively modulated during reconsolidation through an identified endogenous process triggered during a real‐life episode. We propose that the functional value for reconsolidation would be to make possible a change in memory strength by the influence of a concurrent experience. Reconsolidation improvement would lead to memory re‐evaluation, not by altering memory content but by modifying the behaviour as an outcome of changing the hierarchy of the memories that control it.
Design of Shewanella‐specific 16S rRNA primers and application to analysis of Shewanella in a minerotrophic wetland
Authors: Todorova Svetoslava G. , Costello Andria M.
Published: October 2005

In this study, an existing probe was used as a polymerase chain reaction (PCR) primer to study iron‐reducing members of the genus Shewanella in a minerotrophic wetland where iron reduction had previously been implicated. The probe was found to be non‐specific and a new set of PCR primers were developed that were specific for Shewanella. These primers were used to analyse the wetland iron‐reducing communities by characterizing 16S rRNA genes amplified from DNA extracted from peat. Polymerase chain reaction clone libraries were screened using restriction fragment length polymorphism and diagnostic operational taxonomic units for Shewanella species were identified. A statistical method was used to determine the coverage of the clone libraries, which was found to be between 83% and 97%. The dominant species in the wetland samples at two geochemically distinct zones were phylogenetically related to the iron‐reducing microorganism Shewanella oneidensis.
Measurement of Prochlorococcus ecotypes using real‐time polymerase chain reaction reveals different abundances of genotypes with similar light physiologies
Authors: Ahlgren Nathan A. , Rocap Gabrielle , Chisholm Sallie W.
Published: October 2005

Prochlorococcus is a marine cyanobacterium which is found at high abundances in world's tropical and subtropical oligotrophic oceans. The genus Prochlorococcus can be divided into two major groups based on light physiology. Both of these groups can be further subdivided into genetically distinct lineages, or ecotypes. Real‐time polymerase chain reaction (PCR) assays based on sequence differences in the 16S‐23S rDNA internal transcribed spacer or the 23S rDNA were developed to examine the distribution of each ecotype in the field. The real‐time PCR assays enabled linear quantification of concentrations ranging from 10 to 4 × 105 cells ml−1. These assays were applied to a stratified water column in the Sargasso Sea. The majority of Prochlorococcus cells above 110 m belonged to the one of the low chlorophyll b/a ratio (high‐light adapted) ecotypes, while two types of high chlorophyll b/a ratio (low‐light adapted) cells dominated below 110 m. The other three types were found at significantly lower numbers or not detected at all. Differences in the abundance of ecotypes within the major light physiology groupings suggest that other factors, such as nutrient utilization and differential mortality, are driving their relative distributions. Real‐time PCR assays will enable further exploration of these factors and temporal and geographic variability in ecotype abundance.
When Mental Health Becomes Health: Age and the Shifting Meaning of Self‐Evaluations of General Health
Authors: SCHNITTKER JASON
Published: October 2005

Do self‐evaluations of general health change as individuals age? Although several perspectives point to age‐related shifts, few researchers have compared them. For this article, several competing hypotheses were tested using a large, nationally representative, and longitudinal data set. The results suggest two trends. First, the correspondence between functional limitations and self‐rated health declines, especially after age 50. Similarly, the correspondence between various chronic conditions and self‐rated health declines with age. These findings are consistent with social comparison theory. Yet, the results also suggest that the correspondence between depressive symptoms and self‐rated health increases. Indeed, after age 74, the correspondence between self‐rated health and some common symptoms of depression becomes stronger than that between self‐rated health and several chronic, and often fatal, somatic conditions. This crossover has important implications for the detection and treatment of depressive symptoms in later life.
Protecting Neurons
Authors: Ferriero Donna M.
Published: October 2005

Summary:  Brain injury evolves over time, often taking days or even weeks to fully develop. It is a dynamic process that involves immediate oxidative stress and excitotoxicity followed by inflammation and preprogrammed cell death. This article presents a brief overview of mechanisms of neuroprotection in the developing brain. Although the focus is on ischemic injury, the conclusions drawn apply to any type of brain insult—epileptic seizures, trauma, or ischemia.

 Strategies of neuroprotection include salvaging neurons through the use of targeted pharmacotherapies, protecting neurons through preconditioning, and repairing neurons by enhancing neurogenesis. Drug therapies that dampen the impact of immediate and downstream postinjury events are only modestly effective in protecting the brain from ischemic injury. In experimental models, complete or true protection can be achieved only through preconditioning, a process during which an animal develops tolerance to an otherwise lethal stressor. Although of no clinical use, preconditioning models have provided valuable insight into how repair systems work in the brain. Cumulative evidence indicates that the same genes that are upregulated during preconditioning, those mediating true protection, are also upregulated during injury and repair. Specifically, hypoxic preconditioning and hypoxic‐ischemic insult have been shown to induce hypoxia inducible factor‐1 (HIF‐1) and its target survival genes, vascular endothelial growth factor (VEGF), and erythropoietin (Epo) in rodents. Of particular interest is the upregulation of Epo, a growth factor that may have therapeutic potential in the treatment of ischemic stroke. At this time, however, the postinjury enhancement of neurogenesis appears to offer the best hope for long‐lasting functional recovery following brain injury.
Constructing Circuits: Neurogenesis and Migration in the Developing Neocortex
Authors: Kriegstein Arnold R.
Published: October 2005

Summary:  Our knowledge of the proliferation, migration, and differentiation of neurons has changed dramatically over the last 10 years. Whereas traditionally it was thought that glial and neuronal cells were separate cell lines with different lineages, we now know that this is not true. Radial glia are a type of neural stem cell that generate excitatory pyramidal neurons directly through asymmetric cell division in the ventricular zone (VZ) of the telencephalon and indirectly through the symmetric division of daughter intermediate precursor cells that divide in the subventricular zone (SVZ). Moreover, pyramidal neurons, once thought to migrate only along radial guide fibers to the developing layers of the cortex, have been shown to proceed through four distinct stages of migration during which they change shape, direction, and speed. Gamma‐aminobutyric acid (GABAergic) inhibitory interneurons, on the other hand, are generated not in the cortex, but in the medial ganglionic eminence and migrate tangentially to their final cortical destinations. Evidence suggests that GABA activation may play a role in coordinating the generation and migration of both pyramidal and interneuron populations. At the end of neurogenesis, radial glial cells translocate to the cortex and transform into astrocytes. Although they do not actively divide in the adult brain, astrocytes may retain the potential to generate new neurons. These new findings have increased our understanding of the mechanisms underlying certain developmental disorders and, in doing so, reveal potentially useful modes of therapeutic intervention.
Significance of the signal‐to‐cutoff ratios of anti‐hepatitis C virus enzyme immunoassays in screening of Chinese blood donors
Authors: Ren Fu‐Rong , Lv Qiu‐Shuang , Zhuang Hui , Li Jing‐Jing , Gong Xiao‐Yan , Gao Guo‐Jing , Liu Chang‐Li , Wang Jing‐Xing , Yao Fu‐Zhu , Zheng You‐Rong , Zhu Fa‐Ming , Tiemuer Mei‐Hei‐Li , Bai Xu‐Hua , Shan Hua
Published: October 2005

BACKGROUND: The correlation between signal‐to‐cutoff (S/CO) ratios of a second‐generation hepatitis C virus (HCV) enzyme immunoassay (EIA; Abbott) and a third‐generation HCV enzyme‐linked immunosorbent assay (ELISA; Ortho) and confirmed HCV infection has been reported. The utility of the values for the Chinese anti‐HCV EIA kits, however, has not been studied in evaluating test results in Chinese blood donors.

STUDY DESIGN AND METHODS: A total of 156 donor samples repeat reactive for anti‐HCV at routine screening from five representative regions of China were retested for anti‐HCV by the Ortho third‐generation HCV ELISA and six Chinese EIA kits and for HCV RNA by a human immunodeficiency virus‐1 and HCV assay (Procleix, Chiron Corp.). The HCV RNA–nonreactive samples were further tested for anti‐HCV by a third‐generation recombinant immunoblot assay RIBA (Chiron Corp.). The positive result by either nucleic acid amplification test or RIBA was interpreted as confirmed HCV infection.

RESULTS: The confirmed HCV prevalence rate in donors in five representative regions obtained in this study was 0.20 percent (77/37,900) in 2004. All seven anti‐HCV EIA kits had a significant correlation between S/CO ratios and confirmed HCV infection. The threshold S/CO ratios, which predicted more than 95 percent of confirmed HCV infections for the Ortho, SABC, BGI‐GBI, InTec, GWK, KHB, and WANTAI kits, were 3.8, 6.0, 7.0, 8.6, 10.0, 10.0, and 14.0, respectively.

CONCLUSIONS: Anti‐HCV EIA kits commonly used in Chinese donors screening demonstrate good correlation between S/CO ratios and the confirmed infection. For the Ortho third‐generation HCV ELISA, the S/CO ratio of 3.8 determined by the US Centers for Disease Control and Prevention is applicable to Chinese blood donors. The Chinese domestic EIA kits evaluated show a diverse range of threshold S/CO ratios.
Can internal stresses explain the fracture resistance of cusp‐replacing composite restorations?
Authors: Fennis W. M. M. , Kuijs R. H. , Barink M. , Kreulen C. M. , Verdonschot N. , Creugers N. H. J.
Published: October 2005

The aim of this study was to explore and compare the results of occlusal load application to cusp‐replacing composite restorations, studied by means of finite element (FE) analysis and in vitro load tests. A three‐dimensional (3D) FE model was created with a set up similar to an in vitro load test that assessed the fatigue resistance of upper premolars with buccal cusp‐replacing resin composite restorations. Occlusal load was applied to two geometries (with and without palatal cuspal coverage), and the tooth–restoration interface and composite material stresses were calculated. Subsequently, safety factors were calculated by dividing the material strength values by the obtained stresses. The highest safety factors were observed for the restorations with cuspal coverage. This was consistent with the load test, in which cuspal coverage led to higher fracture resistance. Furthermore, the FE analysis predicted that failure of the tooth–restoration interface is more likely than failure of the composite material. Correspondingly, the load test showed predominantly adhesive failures of the restorations. Although the described test methods did not lead to a complete understanding of the failure mechanism, it can be concluded that the FE analysis provides additional information with regard to the differences in fracture behaviour of these types of restorations.
Influence of electron beam irradiation on the alloy‐to‐resin bond strength
Authors: Behr Michael , Rosentritt Martin , Bettermann Klaus , Handel Gerhard
Published: October 2005

The aim of this study was to investigate whether postcuring using electron beam irradiation had an effect on the bond strength of resin‐to‐base‐metal after priming their surfaces using silicoating methods or functional monomers. Composite cylinders were bonded on a restricted area of 5 mm2 to flat rectangular titanium and cobalt‐chromium specimens. Under investigation were the silicoating system Rocatec, the thiol‐phosphate system Metal Primer II and the phosphate ester SR Link. Tensile strength and shear bond strength were determined for the three test groups in each case: (i) after 24 h, (ii) after electron beam irradiation (100 kGy), and (iii) after irradiation (100 kGy) + 12,000 cycles of thermal cycling (5°/55°C). The bond strength was highly affected by irradiation and the metal priming method used. However, the tribochemical silicoating method and phosphate‐ester group showed no significant statistical change in bond strength. Only the thiol‐phosphate system showed considerably higher tensile and shear bond strengths after irradiation. Thermal cycling did not deteriorate this bond and there was a tendency for higher bond strength on titanium. As a result it was determined that thiol‐phosphate primers in combination with postcuring using electron beam irradiation can considerably improve the bond strength between resins and titanium or cobalt‐chromium alloys.
Analysis of gene and protein expression in healthy and carious tooth pulp with cDNA microarray and two‐dimensional gel electrophoresis
Authors: Pääkkönen Virve , Ohlmeier Steffen , Bergmann Ulrich , Larmas Markku , Salo Tuula , Tjäderhane Leo
Published: October 2005

Complementary DNA (cDNA) microarray and two‐dimensional (2‐D) gel electrophoresis, combined with mass spectrometry, enable simultaneous analysis of expression patterns of thousands of genes, but their use in pulp biology has been limited. Here we compared gene and protein expression of pulp tissues from sound and carious human teeth using cDNA microarray and 2‐D gel electrophoresis to evaluate their usefulness in pulp biology research and to identify the genes with changes in carious teeth. The cDNA microarray revealed several differentially expressed genes and genes with a high expression in both tissues. These genes have various functions, e.g. effects on vascular and nerve structures, inflammation, and cell differentiation. Variability between cDNA hybridizations indicates that the overall gene expression pattern may vary significantly between individual teeth. The 2‐D gel electrophoresis revealed no change between healthy and diseased tissue. The identification of 96 proteins in the pulp tissue revealed none of the gene products with corresponding high/different mRNA expression in cDNA microarray. Interestingly, we detected also a hypothetical protein (putative nucleoside diphosphate kinase), and present therefore the first evidence for the existence of this protein. Even though the methods reveal potentially important gene expression, they may currently have only limited value in in vivo pulp biology research.
Variability of flow rate when collecting stimulated human parotid saliva
Authors: Burlage Fred R. , Pijpe Justin , Coppes Rob P. , Hemels Martin E. W. , Meertens Harm , Canrinus Alof , Vissink Arjan
Published: October 2005

The aim of this study was to estimate the accuracy and reproducibility of citric‐acid‐stimulated parotid saliva sampling. In healthy volunteers a strong correlation (r2 = 0.79) between flow rates from the left and right parotid gland was observed. In patients with Sjögren's syndrome this correlation (r2 = 0.90) was even stronger. The intraindividual variation in healthy volunteers was 23.3 ± 5.9%. Increasing the number of collections did not reduce this variation significantly. In head and neck cancer patients, to estimate whether repeated measurements result in more reliable baseline values for use in clinical studies, repeated collections did not result in a significant reduction of intrapatient variation, similar to the results with the healthy volunteers. Thus, notwithstanding the good agreement between left and right flow rates, a high variation in parotid flow rates has to be considered when planning clinical trials evaluating the effects of treatment on salivary gland functioning.
Chronology and regulation of gene expression of RANKL in the rat dental follicle
Authors: Liu D. , Yao S. , Pan F. , Wise G. E.
Published: October 2005

Tooth eruption in the rat requires bone resorption resulting from a major burst of osteoclastogenesis on postnatal day 3 and a minor burst of osteoclastogenesis on postnatal day 10 in the alveolar bone of the first mandibular molar. The dental follicle regulates the major burst on postnatal day 3 by down‐regulating its osteoprotegerin (OPG) gene expression to enable osteoclastogenesis to occur. To determine the role of receptor activator of nuclear factor‐kappa B ligand (RANKL) in tooth eruption, its gene expression was measured on postnatal days 1–11 in the dental follicle. The results show that RANKL expression was significantly elevated on postnatal days 9–11 in comparison to low expression levels at earlier time‐points. As OPG expression is high at this latter time‐point, this increase in RANKL expression would be needed for stimulating the minor burst of osteoclastogenesis. Tumor necrosis factor‐αenhances RANKL gene expressionin vitroand it may be responsible for up‐regulating RANKLin vivo. Transforming growth factor‐β1 and interleukin‐1αalso enhance RANKL gene expressionin vitrobut probably have no effectin vivobecause they are maximally expressed early. Bone morphogenetic protein‐2 acts to down‐regulate RANKL expressionin vitroand,in vivo, may promote alveolar bone growth in the basal region of the tooth.