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1.
The electric organ discharge (EOD) in Brachyhypopomus pinnicaudatus is modified by temperature and reproductive state. We studied the influence of these variables upon a complex behavior, the jamming avoidance response (JAR). Experiments were performed in non-reproductive fish and in two groups of fish after the induction of reproductive state (by nature or by acclimation at 28°C). JARs were elicited at 20 and 30°C by free-run electric stimuli with different Ls (interval difference between stimulus and EOD). In non-reproductive fish, JARs induced by stimuli with +Ls showed temperature sensitivity, with smaller responses at 30°C. Conversely, similar JARs were obtained at both temperatures in reproductive fish. These observations were replicated in curarized preparations. Stimuli with –Ls were almost ineffective in non-reproductive fish at 30°C, whereas adequate JARs were shown by reproductive fish. Phase-locked stimuli were used to evaluate the duration of the low-threshold electrosensory periods preceding and following the EOD. In non-reproductive fish, the temperature step induced a shortening of these periods. The opposite effect was observed in reproductive fish, probably explaining the differences in JAR capability. A prolongation of the low-threshold periods would favor the perception of electrocommunication signals during courtship. JAR changes would be a consequence of this adaptation. 相似文献
2.
Alexis Avril Christian Graff 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(12):1221-1234
Weakly electric fish react to resistance and capacitance of objects that locally amplify and distort their self-generated
Electric Organ Discharge (EOD) received by their skin receptors. The successive-layer structure of tissues gives certain biological
materials a kind of electrical anisotropy. A polarized object, for instance, will conduct current differently in one versus
the other direction. This diode-like electric anisotropy should make a significant difference to a Mormyrid who emits a directional,
biphasic EOD and whose receptors are sensitive to EOD amplitude and distortion changes. The ability of Gnathonemus petersii (Mormyridae) to discriminate polarity was investigated on a virtual object by manipulating changes in a circuit comprised
of diodes combined in various ways. The “novelty response,” an increase in the discharge rate in response to perceived changes,
was used to assess the fish’s sensitivity. Indeed, G. petersii detects polarized objects and discriminates between polarity directions. However, the diode-like anisotropy entails a voltage
threshold. Because voltage decreases with distance, and the EOD comprises opposite phases of different amplitudes, the active
spaces of detection and discrimination are different and depend on the object orientation. Electric polarity thus extends
the “palette” of dielectric properties used by this fish to evaluate object quality, direction, and distance. 相似文献
3.
Extreme sexual dimorphism suggests that the South American electric fish, Brachyhypopomus pinnicaudatus Hopkins (Copeia 1991:151–161, 1991) is polygynous. No field studies have been conducted on the social behavior of this common
gymnotiform species, in part because their nocturnal habits and densely vegetated habitat precludes direct observation in
the field. We conducted mark–recapture studies on B. pinnicaudatus in Uruguay to gather indirect evidence of their breeding system. Sex ratios of adults were highly skewed toward females 2–3 weeks
into the breeding season. Females moved twice as far as males on average (p = 0.016) and movement tracks of individual females overlapped one another but those of males did not. These data support
the hypothesis that B. pinnicaudatus is polygynous or polygynandrous, and suggest that they use space in a manner consistent with exploded lek polygyny or iteroparous
nest site polygynandry models. Fish detected within 2 m of each other were more aggregated than chance, both day and night,
suggesting they maintain social groupings or alerting networks. 相似文献
4.
Bernd Baier 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(10):915-919
The dwarf stonebasher sibling species Pollimyrus castelnaui and P. marianne use differences in the electric organ discharges (EODs) for species recognition. As EOD waveforms are affected by water conductivity changes, the reliability of species recognition might be impeded due to natural variability in the environment. EODs of P. castelnaui (N = 8) and P. marianne (N = 8) under high (250 muS/cm) and low (25 muS/cm) conductivity were recorded and compared. Local peaks of the EODs of both species were significantly and predictably modified due to the conductivity change but species-specific differences were always recognizable. The duration of the EODs was not influenced by the conductivity change. Temperature alterations modified the duration in a linear relationship, allowing the determination of Q (10) values (1.6 for P. castelnaui's and 1.7 for P. marianne's EODs). As the species-specific differences are not masked by conductivity effects, EOD discrimination seems to be a reliable species recognition mechanism under natural circumstances. 相似文献
5.
There are three most important bacterial causative agents of serious infections that could be misused for warfare purposes:
Bacillus anthracis (the causative agent of anthrax) is the most frequently mentioned one; however, Fracisella tularensis (causing tularemia) and Yersinia pestis (the causative agent of plague) are further bacterial agents enlisted by Centers for Disease Control and Prevention into the category A of potential biological weapons. This review intends to summarize basic information about these bacterial
agents. Military aspects of their pathogenesis and the detection techniques suitable for field use are discussed. 相似文献
6.
Martin J. How Jan M. Hemmi 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(12):1053-1061
Male and female animals are not always complicit during reproduction, giving rise to coercion. One example of a system that is assumed to involve sexual coercion is the mate herding behaviour of fiddler crabs: males push females towards the home burrow with the goal of forcing copulation at the burrow entrance. We recorded and analysed in detail the courtship behaviour of a North Australian species of fiddler crab Uca elegans. Courtship was composed of four main phases: broadcast waving, outward run, herding and at burrow display. During interactions males produced claw-waving displays which were directed posteriorly towards the female and which varied in timing and structure depending on the courtship phase. We suggest that courtship herding in U. elegans is driven primarily by mate choice for the following reasons, (1) females can evade herding, (2) no other reproductive strategies were observed, (3) males broadcast their presence and accompany courtship with conspicuous claw waves, and (4) the behaviour ends with the female leading the male into the home burrow. As an alternative function for herding in U. elegans we suggest that the behaviour represents a form of courtship guiding, in which males direct complicit females to the correct home burrow. 相似文献
7.
We observed female beaugregory damselfish (Stegastes leucostictus) as they interacted with males to see whether their movements fit the predictions of different mate-search models. We established
high-quality and low-quality groups with low variance in breeding site quality and a medium-quality, high-variance breeding
site group and compared focal observations of female nonforaging forays in each group. Only 8% of 137 forays monitored resulted
in spawning events. Eighty-nine percent of the forays were less than 240 s and were within 7 m of the focal female’s territory.
Average foray times and straight-line foray distances did not differ for females traveling between males in each group. Females
entered high-quality breeding sites at a higher rate than low-quality sites and round-trip distances were also greatest in
high-quality groups, indicating that females were following a more convoluted path. We interpret these results to mean that
(a) female beaugregories separate the tasks of mate assessment and mate choice by conducting information-gathering forays
between mating events, (b) forays are energetically costly and therefore usually short in duration and overall distance traveled,
(c) information collection takes approximately the same time for high-quality and low-quality mates, but (d) females will
alter their foray patterns in high-quality areas to collect additional information. These data are also consistent with the
hypothesis that females optimize their search by employing a tiered process of assessment during information-gathering forays,
first using an adjustable threshold to accept or reject each male based on his courtship and subsequently a fixed threshold
to assess the quality of each breeding site. 相似文献
8.
The intron sequence of chloroplast rpS16 and the secondary structure of its pre-mRNA were characterized for the first time in 26 Allium sativum accessions of different ecologo-geographical origins and seven related Allium species. The boundaries and main stem-loop consensus sequences were identified for all six domains of the intron. Polymorphism
was estimated for the total intron and its regions. The structural regions of the rpS16 intron proved to be heterogeneous for mutation rate and spectrum. Mutations were most abundant in domains II and IV, and
transition predominated in domains I, III, V, and VI. In addition to structural elements and motifs typical for group IIB
introns, several Allium-specific micro- and macrostructural mutations were revealed. A 290-bp deletion involving domains III and IV and part of domain
V was observed in A. altaicum, A. fistulosum, and A. schoenoprasum. Several indels and nucleotide substitutions were found to cause a deviation of the pre-mRNA secondary structure from the
consensus model of group II introns. 相似文献
9.
O. V. Golovanova V. I. Konenkov A. V. Shevchenko M. V. Smolnikova 《Russian Journal of Genetics》2009,45(8):981-986
Based on population analysis of the DRB1, DQA1, DQB1 and TNFA allele frequency distribution patterns, regional features of immunogenetic structure of the population of West Siberia were
investigated. Statistically significant linkage disequilibrium within the HLA class II region, as well as between the TNFA and DRB1, DQA1, and DQB1 was demonstrated. Population frequency distribution patterns of two- and multilocus haplotypes were examined. 相似文献
10.
N. Yu. Markelova 《Microbiology》2010,79(6):777-779
Interaction of Bdellovibrio bacteriovorus 100NCJB with bacteria Campylobacter jejuni (strains 1, 2, 3, 4, and 5) and Helicobacter pylori, strain TX30a, was confirmed. The results indicate that lytic activity of bdellovibrios both in liquid media and cells attached
to a surface was observed. The potential use of the antimicrobial activity of predatory bacteria for environmental bioprotection
and public health is discussed. 相似文献
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To overexpress the chitosanase gene (csn) in F. solani, a vector based on pCAMBIA 1300 was constructed. The csn gene, which is under control of the Aspergillus nidulans
gpdA promoter and A. nidulans trpC terminator, was introduced back into the F. solani genome by Agrobacterium tumefaciens-mediated transformation, and the herbicide-resistance gene bar from Streptomyces hygroscopicus was used as the selection marker. Transformants which showed a significant increase in chitosanase production (~2.1-fold
than control) were obtained. Southern blot analysis indicated that most transformants had a single-copy T-DNA integration. 相似文献
15.
I. Rosario G. Soro S. Déniz O. Ferrer F. Acosta D. Padilla B. Acosta 《Mycopathologia》2010,169(4):315-319
Columba livia is an important reservoir and carrier of Cryptococcus neoformans, Cryptococcus uniguttulatus, Cryptococcus laurentii and Cryptococcus albidus. Upper digestive tract of this species is also known as a habitat for Cryptococcus neoformans. Given the increasing clinical interest of this microorganism, 331 swabs from crop and 174 dropping samples from pigeon lofts
in Grand Canary Island have been studied. The obtained results show an extensive presence samples 81 positive (24.47%) of
Cryptococcus spp. in analysed crops: 32 (9.66%) for C. neoformans, 24 (7.2%) for C. uniguttulatus, 23 (6.9%) for C. albidus and 2 (0.6%) for C. laurentii. In the same way, Cryptococcus spp was also isolated in 82 (47.13%), dropping samples: C. neoformans in 59 (33.9%), C. uniguttulatus, in 9 (5.17%), C. laurentii in 8 (4.59%) and C. albidus in 6 (3.44%) of the investigated samples, respectively. The cryptococcosis produced by species of cryptococci other than C. neoformans has become more important during the last decade, supporting the study on the role of pigeon in the epidemiology of this
disease. 相似文献
16.
Hiroyoshi Kubo 《Mycoscience》2009,50(5):400-406
Pilobolus crystallinus shows unique photoresponses at various growing stages. cDNAs for putative photoreceptors were cloned from this fungus. Three
genes named pcmada1, pcmada2, and pcmada3 were identified from the PCR fragments, and amplified with degenerated primers for the LOV domain, which is conserved in
many blue-light receptors. Deduced amino acid sequences for PCMADA1, PCMADA2, and PCMADA3 had one light-oxygen-voltage (LOV)-sensing
and two PER-ARNT-SIM (PAS) domains. A zinc finger DNA-binding motif was conserved in the C-terminals of PCMADA1 and PCMADA3.
However, PCMADA2 lacked the zinc finger motif. Expression of pcmada1 was suppressed by blue light whereas that of pcmada3 was promoted by blue-light irradiation. 相似文献
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D. V. Fedorov S. V. Kovaltzova V. T. Peshekhonov V. G. Korolev 《Russian Journal of Genetics》2010,46(6):659-665
The yeast genes IXR1 and HMO1 encode proteins belonging to the family of chromatin nonhistone proteins, which are able to recognize and bind to irregular
DNA structures. The full deletion of gene IXR1 leads to an increase in cell resistance to the lethal action of UV light, γ-rays, and MMS, increases spontaneous mutagenesis and significantlly decreases the level of UV-induced mutations. It was earlier
demonstrated in our works that the hmo1 mutation renders cells sensitive to the lethal action of cisplatin and virtually does not affect the sensitivity to UV light.
Characteristically, the rates of spontaneous and UV-induced mutagenesis in the mutant are increased. Epistatic analysis of
the double mutation hmo1 ixr1 demonstrated that the interaction of these genes in relation to the lethal effect of cisplatin and UV light, as well as UV-induced
mutagenesis, is additive. This suggests that the products of genes HMO1 and IXR1 participate in different repair pathways. The ixr1 mutation significantly increases the rate of spontaneous mutagenesis mediated by replication errors, whereas mutation hmo1 increases the rate of repair mutagenesis. In wild-type cells, the level of spontaneous mutagenesis was nearly one order of
magnitude lower than that obtained in cells of the double mutant. Consequently, the combined activity of the Hmo1 and the
Ixr1 proteins provides efficient correction of both repair and replication errors. 相似文献