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71.
An early winged crown group stick insect from the Early Eocene amber of France (Insecta,Phasmatodea)
ANDRÉ NEL EMMANUEL DELFOSSE TONY ROBILLARD JULIAN F. PETRULEVIČIUS 《Systematic Entomology》2010,35(2):340-346
The new stick insect family Gallophasmatidae, based on Gallophasma longipalpis gen. et sp.n. , from the Earliest Eocene French amber has a pattern of tegmina venation typical of Archaeorthoptera, also present in at least some Mesozoic ‘Phasmatodea’. On the other hand, Gallophasma displays in its body anatomy some apomorphies of the extant Euphasmatodea, e.g. fusion of metatergum and abdominal tergum 1, correlated with the reduction of abdominal sternum 1 to lateral triangular sclerites. A unique autapomorphy of Gallophasma is the presence of annulated and apparently multi‐segmented or pseudo‐segmented cerci; all other Phasmatodea have one‐segmented cerci. The venation of the tegmina of Gallophasma differs from that of extant winged Phasmatodea in the plesiomorphic absence of a knob‐like dorsal eversion. This and other differences in the wing venation between extant and extinct Phasmatodea might have been caused by the loss of wings at some point in the evolutionary history of the order and their secondary gain in a subclade of the extant phasmids. 相似文献
72.
FRÉDÉRIC LEGENDRE TONY ROBILLARD HOJUN SONG MICHAEL F. WHITING LAURE DESUTTER‐GRANDCOLAS 《Systematic Entomology》2010,35(3):475-488
Although Ensifera is a major insect model group, its phylogenetic relationships have been understudied so far. Few phylogenetic hypotheses have been proposed, either with morphological or molecular data. The largest dataset ever used for phylogeny reconstruction on this group is molecular (16S rRNA, 18S rRNA and 28S rRNA sequences for 51 ensiferan species), which has been used twice with different resultant topologies. However, only one of these hypotheses has been adopted commonly as a reference classification. Here we re‐analyse this molecular dataset with different methods and parameters to test the robustness and the stability of the adopted phylogeny. Our study reveals the instability of phylogenetic relationships derived from this dataset, especially for the deepest nodes of the group, and suggests some guidelines for future studies. The comparison between the different classifications proposed in the past 70 years for Ensifera and our results allows the identification of potential monophyletic clades (katydids, mole crickets, scaly crickets + Malgasia, true crickets, leaf roller crickets, cave crickets) and the remaining unresolved clades (wetas, Jerusalem crickets and most of the highest rank clades) in Ensifera phylogeny. 相似文献
73.
Ricardo Fagundes da Rocha Marcos Roberto de Oliveira Matheus Augusto de Bittencourt Pasquali Michael Éverton Andrades Max William Soares Oliveira Guilherme Antônio Behr José Cláudio Fonseca Moreira 《Cell biochemistry and function》2010,28(3):190-196
Exercise training has been used for treatment/prevention of many cardiovascular diseases, but the mechanisms need to be clarified. Thus, our aim was to compare oxidative stress parameters between rats submitted to a swimming training and sedentary rats (control). Twelve male rats were divided into two groups: control and exercise training. The exercise training had daily 1 h swimming sessions for 8 weeks and a load (5% of its body mass) was placed in rat's tail. Thereafter the animals were killed, aorta and heart were surgically removed and blood was collected. Body mass gain, thiobarbituric acid reactive species (TBARS), carbonyl content, total reactive antioxidant potential (TRAP), total antioxidant reactivity (TAR), superoxide dismutase (SOD) activity and catalase (CAT) activity were evaluted. The trained rats showed a lower body mass gain and no modifications on heart. An increased SOD activity was observed on aorta after the training, but no changes were seen for CAT activity, which led to an increased SOD/CAT ratio. The arterial TBARS was also increased for trained rats. The decrease in TRAP in exercise training was the single modification on plasma. Our findings suggest that the increased SOD activity could play a role in vascular adaptations to exercise training. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
74.
Bilodeau M Tousignant J Ethier C Rocheleau B Raymond VA Lapointe R 《Apoptosis : an international journal on programmed cell death》2004,9(5):609-617
Liver growth factors are known to be anti-apoptotic for hepatocytes. The potential of insulin, a liver co-mitogen, has not been thoroughly evaluated. We studied the anti-apoptotic role of insulin on primary cultures of rat hepatocytes exposed to transforming growth factor-beta (TGF-beta) as the apoptotic agent and in the left portal vein ligation model (LVPL) of liver atrophy. Results show that insulin decreases apoptosis of TGF-beta-treated hepatocyte cultures by 43% (P < 0.002) and the alanine amino transferase (ALT) release by 49% (P < 0.001). Left lobes of LPVL animals displayed a significant increase in the levels of TGF-beta mRNA. In LPVL rats receiving continuous infusion of insulin in the left lobes, the weight of the atrophic lobes was higher over a 7-day period in comparison to control animals. This was associated with lower levels of serum ALT and with a five-fold decrease in the apoptotic index in the left lobes (P < 0.0001). Induction of Akt phosphorylation and increased expression of Bcl-xl were observed in the left lobes of insulin-treated animals. In conclusion, these results show that insulin is anti-apoptotic for normal hepatocytes both in vitro and in vivo and that the action of insulin is associated with increased Bcl-xl expression and Akt activation. 相似文献
75.
During different behavioral states different population activities are present in the hippocampal formation. These activities
are not independent: sharp waves often occur together with high-frequency ripples, and gamma-frequency activity is usually
superimposed on theta oscillations. There is both experimental and theoretical evidence supporting the notion that gamma oscillation
is generated intrahippocampally, but there is no generally accepted view about the origin of theta waves. Precise timing of
population bursts of pyramidal cells may be due to a synchronized external drive. Membrane potential oscillations recorded
in the septum are unlikely to fulfill this purpose because they are not coherent enough. We investigated the prospects of
an intrahippocampal mechanism supplying pyramidal cells with theta frequency periodic inhibition, by studying a model of a
network of hippocampal inhibitory interneurons. As shown previously, interneurons are capable of generating synchronized gamma-frequency
action potential oscillations. Exciting the neurons by periodic current injection, the system could either be entrained in
an oscillation with the frequency of the inducing current or exhibit in-phase periodic changes at the frequency of single
cell (and network) activity. Simulations that used spatially inhomogeneous stimulus currents showed anti-phase frequency changes
across cells, which resulted in a periodic decrease in the synchrony of the network. As this periodic change in synchrony
occurred in the theta frequency range, our network should be able to exhibit the theta-frequency weakening of inhibition of
pyramidal cells, thus offering a possible mechanism for intrahippocampal theta generation.
Received: 23 February 2000 / Accepted in revised form: 30 June 2000 相似文献
76.
Tóth EC Vissi E Kovács I Szöke A Ariño J Gergely P Dudits D Dombrádi V 《Plant molecular biology》2000,43(4):527-536
We detected an about 200 kDa holoenzyme of protein phosphatase 2A (PP2A) in the crude extract of Medicago sativa microcallus cells by gel permeation chromatography. By polymerase chain reaction (PCR) we isolated two M. sativa cDNA fragments corresponding to the catalytic (C) subunit, and one each coding for the A and the B regulatory subunits of PP2A. The C subunit sequences were different from that published previously, indicating the existence of at least three different isoforms in M. sativa. Using the PCR fragments as probes, we obtained two distinct full-length clones for both the A and B subunits from an alfalfa cDNA library. Our results demonstrate that the components of the PP2A holoenzyme, namely the catalytic and regulatory subunits, are present in alfalfa in several isoforms and that their sequences are highly similar to their plant, yeast and animal counterparts. The distinct regulatory subunit genes are constitutively expressed during the cell cycle. Interestingly, two A-B subunit pairs had parallel mRNA steady-state levels in different plant tissues suggesting that not all of the possible isoform combinations are present in all tissues. The expression of the MsPP2A B subunit form was induced by abscisic acid indicating a specific function for this protein in the stress response. 相似文献
77.
78.
ANDERS MALMER DANIEL MURDIYARSO L. A. BRUIJNZEEL ULRIK ILSTEDT 《Global Change Biology》2010,16(2):599-604
Tree planting in the tropics is conducted for a number of reasons including carbon sequestration, but often competes with increasingly scarce water resources. The basics of forest and water relations are frequently said to be well understood but there is a pressing need to better understand and predict the hydrological effects of land‐use and climate change in the complex and dynamic landscapes of the tropics. This will remain elusive without the empirical data required to feed hydrological process models. It is argued that the current state of knowledge is confused by too broad a use of the terms ‘forest’ and ‘(af)forestation’, as well as by a bias towards using data generated mostly outside the tropics and for nondegraded soil conditions. Definitions of forest, afforestation and reforestation as used in the climate change community and their application by land and water managers need to be reconciled. 相似文献
79.
HÉCTOR BOTELLA JOSÉ I. VALENZUELA‐RÍOS CARLOS MARTÍNEZ‐PÉREZ 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2009,42(3):365-376
The continuous replacement of teeth throughout their lifetime is a common characteristic of most chondrichthyans. This process was already present in the earliest representatives of the group. It has been well established that different species of extant sharks show rapid tooth replacement rates; however, some authors have suggested that in early chondrichthyans this rate might have been much slower. Here we present a qualitative approach to analyse tooth replacement rates in the Early Devonian shark Leonodus carlsi , the earliest tooth-bearing shark known to date. For this, we have examined 1,103 isolated teeth from Celtiberia, Spain. Our study provides strong evidences of an extremely slow dental replacement in this primitive chondrichthyan based on three independents analyses: (1) statistical analysis of the wear degree, demonstrating that teeth remain functional for a long period of time; (2) analysis of both the histological and the morphological features of the teeth cusps suggests that this chondrichthyan used a maturation process that optimizes its function, thus worn teeth show an efficient working shape that implies their teeth remained functional for a long time after being modelled by use; and (3) estimations of size increments between teeth (Δs) of the same dental family for some recent sharks whose rates of replacement were known prove that Δs is inversely proportional to the rate of replacement ( R 2 = 0.8327). The estimated values of tooth replacement rates obtained from Δs for L. carlsi and for some Late Devonian cladoselachian sharks are significatively slower than those observed in current sharks. 相似文献
80.
GABRIELA A. PINTO‐JUMA JOSÉ A. QUARTAU MICHAEL W. BRUFORD 《Zoological Journal of the Linnean Society》2009,155(2):266-288
Cicadas are widely distributed in the Mediterranean area and are mainly distinguished by male acoustic signals, which act as specific mate recognition systems. Within the genus Cicada L. several species have diverged in their calling songs without showing external morphological differences, so acoustic recordings and genetic studies are particularly useful for systematic, biogeography and evolutionary studies. This study assesses sequence variation in closely related species of Cicada from the Mediterranean area, using domain III of the 12S rRNA mitochondrial gene in order to determine the phylogenetic relationships and the evolutionary history of this group, as well as the population structure of the two most common species, C. orni and C. barbara. Five distinct haplogroups were identified, C. orni, C. barbara, C. mordoganensis, C. cretensis and C. lodosi, each corresponding to a distinct evolutionary group. C. barbara was the most divergent species within this group, while C. orni and C. mordoganensis were the most similar. The population structure and demographic parameters of the species were not completely resolved. However, there is evidence for the separation of the C. orni Greek populations from the rest of Europe and also for demographic expansions probably related to Pleistocene climate changes. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 266–288. 相似文献