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MIKIHIKO KOGO SUSUMU TANAKA SCOTT CHANDLER TOKUZO MATSUYA 《Somatosensory & motor research》2013,30(3):200-210
An in vitro jaw-attached brainstem preparation was developed to investigate the relationship between jaw opener and closer muscle activity during chemically induced rhythmical jaw movements in neonatal rats. In the majority of preparations examined, where a defined region of brainstem was isolated and the neuronal innervation of the jaw opener and closer muscles was left intact, bath application of the excitatory amino acid agonist N -methyl-D,L-aspartate (NMA, 20-40 muM) in combination with bicuculline (BIC 10 muM), a GABAA antagonist, produced rhythmical electromyogram (EMG) activity in jaw opener and closer muscles, bilaterally, in conjunction with rhythmical jaw movements. Low concentrations of NMA (20 muM) in combination with BIC produced temporally coordinated activity between the jaw opener and closer muscles, ipsilaterally. With higher doses of NMA (40 muM), each muscle group exhibited bursting, but temporal coordination between them was difficult to establish. Similarly, NMA application in combination with the glycine antagonist strychnine (STR, 10 muM), also produced rhythmical EMG activity from both opener and closer muscles, ipsilaterally, but showed no temporal coordination between the antagonist muscle pair. However, coordination of opener and closer muscle discharge could be restored by the addition of BIC to the bath. We suggest that there exist separate, but coordinated, rhythm generator circuits for opener and closer motoneuronal discharge located in close proximity to the trigeminal motor nucleus and under GABAergic control for production of temporal coordination between rhythmogenic circuits. 相似文献
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Patterns of chloroplast DNA (cpDNA) and mitochondrial DNA (mtDNA) variation
were studied in 378 populations of oak trees sampled throughout the
southern half of France. Six cpDNA haplotypes detected in a previous
European survey and three new cpDNA haplotypes were found in this region.
Two mitochondrial polymorphisms detected earlier by restriction analysis of
PCR-amplified fragments alone, or in combination with single-strand
conformation polymorphism (SSCP), were compared with the cpDNA data.
Sequencing revealed the nature of the two mitochondrial mutations: a
single-base substitution and a 4-bp inversion associated with a 22-bp
hairpin secondary structure. The single-base substitution was then analyzed
by allele-specific amplification. Results for the two cytoplasmic genomes
were combined, which allowed the identification of 12 cpDNA-mtDNA
haplotypes. The 4-bp mtDNA inversion has appeared independently in
different cpDNA lineages. Given the peculiar nature of this mtDNA mutation,
we suggest that intramolecular recombination leading to repeated inversions
of the 4-bp sequence (rather than paternal leakage of one of the two
genomes) is responsible for this pattern. Furthermore, the geographic
locations of the unusual cpDNA-mtDNA associations (due to the inversion)
usually do not match the zones of contact between divergent haplotypes. In
addition, in southern France, the groupings of populations based on the
mtDNA substitution were strictly congruent with those based on cpDNA.
Because many populations that are polymorphic for both cpDNA and mtDNA have
remained in contact since postglacial recolonization in this area without
producing any new combination of cytoplasms involving the mitochondrial
substitution, we conclude that paternal leakage is not a significant factor
at this timescale. Such results confirm and expand our earlier conclusions
based on controlled crosses.
相似文献
75.
PETER J. CHANDLER 《Systematic Entomology》1980,5(1):27-41
Abstract. The validity and composition of Ectrepesthoneura Enderlein are discussed and it is contrasted with the related genus Tetragoneura Winnertz. The occurrence of mid-tibial sense organs in these genera and elsewhere in the subfamily Sciophilinae is considered. The European Ectrepesthoneura are revised and the secondary sexual characters of the male legs newly described. Two sgecies, E.pubescens (Zetterstedt ) = messaurensis Plassmann, syn.n. and E.colyeri sp.n., are added to the British list. The Nearctic species are discussed and the two eastern species dealt with fully: the male of E.bicolor (Coquillett) is newly recognized and Elaffooni sp.n. described. Some western Nearctic Tetragoneura probably belong correctly to Ectrepesthoneura but examination of types showed that T.quintana Cole, T.longicauda van Duzee and the eastern Nearctic T.pimpla Coquillett belong to Dziedzickia Johannsen in its present broad usage. The Palaearctic Ectrepesthoneura gracilis Edwards also probably has closer affinities with Dziedzickia than with its present assignment. The Japanese Ectrepesthoneura described by Sasakawa (1961) are excluded as they are probably Sciaridae. 相似文献
76.
MH Bowie J Klimaszewski CJ Vink S Hodge SD Wratten 《New Zealand journal of zoology.》2013,40(4):268-284
Pitfall traps were used to monitor predatory arthropod numbers along two types of field boundary, a post and wire fence line and a Cupressus macrocarpa hedge, along the same paddock margin in Canterbury, New Zealand, over 24 months. The seven most abundant predator groups recorded were: Araneae > Phalangiidae > Staphylinidae > Coccinellidae > Chilopoda > Hemerobiidae > Carabidae. Araneae, Phalangiidae, Staphylinidae, Chilopoda and Hemerobiidae were found in larger numbers at the wire fence than at the hedge site, whereas the numbers of Carabidae and Coccinellidae adults exhibited no field margin preference. However, more species of Araneae and Staphylinidae were caught at the hedge site, whereas species richness of carabid beetles was greatest at the wire fence. Principal component analysis clearly separated the samples collected from the two habitats based on the assemblages of Araneae, Staphylinidae and Carabidae, and certain species in each of these taxonomic groups appeared to be particularly associated with one boundary type or the other. All the main taxonomic groups exhibited clear seasonal patterns, with distinct peaks in abundance occurring at certain times of the year. The results of the study reinforce the idea that management of field boundaries can be used to manipulate the type and abundance of particular groups of predatory arthropods, and that seasonal patterns should be taken into account in schemes of integrated pest management so that any adverse effects of biocide application on these beneficial species may be minimised. 相似文献
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GLUTAMINE SYNTHETASE ISOFORMS IN ALGAE 总被引:5,自引:5,他引:0