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61.
Philip W. Bateman Lauren N. Gilson & J. W. H. Ferguson 《Ethology : formerly Zeitschrift fur Tierpsychologie》2001,107(12):1087-1098
Although there is a corpus of evidence that females of many taxa are choosy about males, there is less information on how males may react to females of different 'quality' (i.e. potential fecundity). The cricket Gryllodes sigillatus shows distinct mate guarding behaviour. We examined how long males mate guard females of different sizes (reflecting egg load and potential fecundity). We also examined the sperm number in ampullae donated to females of different sizes to see if males make a concomitant difference in investment in ejaculate. We also examined mate-guarding behaviour and ejaculate size of males mated to virgin and nonvirgin females of the same size to see if males equate size with increased age and increased likelihood of mating (increased sperm competition). The results showed that males mate guard larger females for longer but make no difference in ejaculate investment between sizes of female. Males make no significant difference in mate guarding investment or ejaculate investment between virgins and nonvirgins of the same size. There is evidence that other species of crickets do alter their ejaculate depending on the female size and mating history, but have less distinct guarding behaviour. We suggest that mate-guarding investment in G. sigillatus may serve a similar function to that of ejaculate investment in other crickets. 相似文献
62.
Amiloride does not alter NaCl avoidance in Fischer-344 rats 总被引:2,自引:2,他引:0
Fischer-344 (F-344) rats differ from other common rat strains in that they
fail to show any preference for NaCl at any concentration in two- bottle
preference tests. Because 100 microM amiloride partially blocks the
NaCl-evoked chorda tympani (CT) response in electrophysiological studies,
we tested NaCl preference (0.068-0.273 M) in F-344 rats with and without
100 microM amiloride solution as the solvent. A third group was tested with
unadulterated NaCl solutions following CT transection. Amiloride had no
significant effect on the NaCl preference-aversion function, whereas CT
transection significantly reduced NaCl avoidance. These results suggest
that the amiloride-sensitive component of the NaCl response is not
necessary for F-344 rats to display avoidance of NaCl, but the entire CT
input is.
相似文献
63.
Guillaume Gaullier Simona Miron Sabrina Pisano Rémi Buisson Yann-Va? Le?Bihan Carine Tellier-Lebègue Wala Messaoud Pierre Roblin Beatriz G. Guimar?es Robert Thai Marie-Josèphe Giraud-Panis Eric Gilson Marie-Hélène Le?Du 《Nucleic acids research》2016,44(4):1962-1976
Telomere integrity is essential to maintain genome stability, and telomeric dysfunctions are associated with cancer and aging pathologies. In human, the shelterin complex binds TTAGGG DNA repeats and provides capping to chromosome ends. Within shelterin, RAP1 is recruited through its interaction with TRF2, and TRF2 is required for telomere protection through a network of nucleic acid and protein interactions. RAP1 is one of the most conserved shelterin proteins although one unresolved question is how its interaction may influence TRF2 properties and regulate its capacity to bind multiple proteins. Through a combination of biochemical, biophysical and structural approaches, we unveiled a unique mode of assembly between RAP1 and TRF2. The complete interaction scheme between the full-length proteins involves a complex biphasic interaction of RAP1 that directly affects the binding properties of the assembly. These results reveal how a non-DNA binding protein can influence the properties of a DNA-binding partner by mutual conformational adjustments. 相似文献
64.
Figueiredo Douglas B. Carvalho Eneas Santos Mauricio P. Kraschowetz Stefanie Zanardo Rafaela T. Campani Gilson Silva Gabriel G. Sargo Cíntia R. Horta Antonio Carlos L. de C. Giordano Roberto Miyaji Eliane N. Zangirolami Teresa C. Cabrera-Crespo Joaquin Gonçalves Viviane Maimoni 《Applied microbiology and biotechnology》2017,101(6):2305-2317
Applied Microbiology and Biotechnology - Streptococcus pneumoniae is the main cause of pneumonia, meningitis, and other conditions that kill thousands of children every year worldwide. The... 相似文献
65.
Ie-Bin Lian Yi-Hsien Lin Ying-Chao Lin Hsin-Chou Yang Chee-Jang Chang Cathy SJ Fann 《BMC bioinformatics》2008,9(1):246
Background
Association testing is a powerful tool for identifying disease susceptibility genes underlying complex diseases. Technological advances have yielded a dramatic increase in the density of available genetic markers, necessitating an increase in the number of association tests required for the analysis of disease susceptibility genes. As such, multiple-tests corrections have become a critical issue. However the conventional statistical corrections on locus-specific multiple tests usually result in lower power as the number of markers increases. Alternatively, we propose here the application of the longest significant run (LSR) method to estimate a region-specific p-value to provide an index for the most likely candidate region. 相似文献66.
Hsin-Chou Yang Mei-Chu Huang Ling-Hui Li Chien-Hsing Lin Alice LT Yu Mitchell B Diccianni Jer-Yuarn Wu Yuan-Tsong Chen Cathy SJ Fann 《BMC bioinformatics》2008,9(1):196
Background
Microarray-based pooled DNA experiments that combine the merits of DNA pooling and gene chip technology constitute a pivotal advance in biotechnology. This new technique uses pooled DNA, thereby reducing costs associated with the typing of DNA from numerous individuals. Moreover, use of an oligonucleotide gene chip reduces costs related to processing various DNA segments (e.g., primers, reagents). Thus, the technique provides an overall cost-effective solution for large-scale genomic/genetic research. However, few publicly shared tools are available to systematically analyze the rapidly accumulating volume of whole-genome pooled DNA data. 相似文献67.
The telomeres protect the end of chromosomes from being recognized and processed as an accidental double stranded break. In human somatic cells, telomeres shorten progressively with every round of DNA replication, leading to dysfunctional telomeres that trigger cellular senescence or apoptosis depending on the cell type. This telomere erosion appears to play a role in cell renewal, ageing and cancer. Two recent studies demonstrated in mouse that eroded telomeres in cancer cells blocked for apoptosis limit cancer formation by triggering senescence. These results suggest that provoking senescence may provide a way to cure cancer and point to new therapeutical strategies targeting specific telomeric functions. Nevertheless, an important question remains unanswered: does replicative senescence limit tumor formation in human? 相似文献
68.
Schiar VP Dos Santos DB Paixão MW Nogueira CW Rocha JB Zeni G 《Chemico-biological interactions》2009,177(1):28-33
Oxidative stress can induce complex alterations of membrane proteins in red blood cells (RBCs) eventually leading to hemolysis. RBCs represent a good model to investigate the damage induced by oxidizing agents. Literature data have reported that chalcogen compounds can present pro-oxidant properties with potent inhibitory effects on cell growth, causing tissue damage and inhibit a variety of enzymes. In this study, human erythrocytes were incubated in vitro with various chalcogen compounds at 37 °C: diphenyl ditelluride (1), dinaphthalen diteluride (2), diphenyl diselenide (3), (S)-tert-butyl 1-diselenide-3-methylbutan-2-ylcarbamate (4), (S)-tert-butyl 1-diselenide-3-phenylpropan-2-ylcarbamate (5), selenium dioxide (6) and sodium selenite (7) in order to investigate their potential in vitro toxicity. After 6 h of incubation, all the tested compounds increased the hemolysis rate, when compared to control and compound (2) had the most potent hemolytic effect. The addition of reduced glutathione (GSH) or glucose to the incubation medium enhanced hemolysis caused by chalcogen compounds. The thiol oxidase activity of these compounds was evaluated by measuring the rate of cysteine (CYS) and dithiotreitol (DTT) oxidation. DTT and cysteine oxidation was increased by all the compounds tested. The results suggest a relationship between the oxidation of intracellular GSH and subsequent generation of free radicals with the hemolysis by chalcogen compounds. 相似文献
69.
Matthieu Gilson Anthony N. Burkitt David B. Grayden Doreen A. Thomas J. Leo van Hemmen 《Biological cybernetics》2009,101(2):103-114
Spike-timing-dependent plasticity (STDP) is believed to structure neuronal networks by slowly changing the strengths (or weights)
of the synaptic connections between neurons depending upon their spiking activity, which in turn modifies the neuronal firing
dynamics. In this paper, we investigate the change in synaptic weights induced by STDP in a recurrently connected network
in which the input weights are plastic but the recurrent weights are fixed. The inputs are divided into two pools with identical
constant firing rates and equal within-pool spike-time correlations, but with no between-pool correlations. Our analysis uses
the Poisson neuron model in order to predict the evolution of the input synaptic weights and focuses on the asymptotic weight
distribution that emerges due to STDP. The learning dynamics induces a symmetry breaking for the individual neurons, namely
for sufficiently strong within-pool spike-time correlation each neuron specializes to one of the input pools. We show that
the presence of fixed excitatory recurrent connections between neurons induces a group symmetry-breaking effect, in which
neurons tend to specialize to the same input pool. Consequently STDP generates a functional structure on the input connections
of the network. 相似文献
70.
Matthieu Gilson Anthony N. Burkitt David B. Grayden Doreen A. Thomas J. Leo van Hemmen 《Biological cybernetics》2009,101(2):81-102
Spike-timing-dependent plasticity (STDP) determines the evolution of the synaptic weights according to their pre- and post-synaptic
activity, which in turn changes the neuronal activity. In this paper, we extend previous studies of input selectivity induced
by (STDP) for single neurons to the biologically interesting case of a neuronal network with fixed recurrent connections and
plastic connections from external pools of input neurons. We use a theoretical framework based on the Poisson neuron model
to analytically describe the network dynamics (firing rates and spike-time correlations) and thus the evolution of the synaptic
weights. This framework incorporates the time course of the post-synaptic potentials and synaptic delays. Our analysis focuses
on the asymptotic states of a network stimulated by two homogeneous pools of “steady” inputs, namely Poisson spike trains
which have fixed firing rates and spike-time correlations. The (STDP) model extends rate-based learning in that it can implement,
at the same time, both a stabilization of the individual neuron firing rates and a slower weight specialization depending
on the input spike-time correlations. When one input pathway has stronger within-pool correlations, the resulting synaptic
dynamics induced by (STDP) are shown to be similar to those arising in the case of a purely feed-forward network: the weights
from the more correlated inputs are potentiated at the expense of the remaining input connections. 相似文献