Divergent Preferences for Song Structure between a Field Cricket and its Phonotactic Parasitoid

In many animals, males produce signals to attract females for mating. However, eavesdropping parasites may exploit these conspicuous signals to find their hosts. In these instances, the strength and direction of natural and sexual selection substantially influence song evolution. Male variable field crickets, Gryllus lineaticeps, produce chirped songs to attract mates. The eavesdropping parasitoid fly Ormia ochracea uses cricket songs to find its hosts. We tested female preferences for song structure (i.e., chirped song vs. trilled song) in crickets and flies using choice experiments. Female crickets from a parasitized and a non-parasitized population significantly preferred the species-typical chirped song, whereas flies significantly preferred a trilled song, which is expressed by other hosts in different regions. Sexual selection due to female choice and natural selection due to fly predation both appear to favor the chirped song structure of G. lineaticeps in the parasitized population, whereas sexual selection favors the chirped structure in the non-parasitized population.     

Broad Selectivity for Courtship Song in the Cricket Gryllus bimaculatus

Various characteristics of a long‐distance acoustic signal have been shown to vary to different degrees. It has been suggested that female preferences based on stable song parameters are stabilising or weakly directional, and preferences based on variable parameters are strongly directional. We tested this hypothesis based on a short‐distance signal (courtship song) produced by the field cricket, Gryllus bimaculatus. We studied the degree of variability of different courtship song parameters and the behavioural importance of several parameters using synthesised song models in playback experiments. We found that most of the courtship song elements of G. bimaculatus were quite variable (coefficient of variation, CV, in the range of 20–53%). The most variable parameter of the courtship song was the relative amplitude of two elements: high‐amplitude ticks and low‐amplitude pulses. Because songs containing only ticks (of rare occurrence) appeared to be more effective than songs with both ticks and pulses (of frequent occurrence), we consider female preferences to be directional. Alteration of less variable traits, such as the carrier frequency and duration of ticks (CV = 20–25%), had a different effect on female responsiveness. The synthesised songs with different carrier frequencies of ticks were as attractive to females as the positive control (courtship of muted males accompanied by playback of the recorded song). Altering the duration of ticks had a crucial effect on the female response rate, decreasing female responsiveness to the level observed in the negative control (courtship of muted males). Thus, we did not find a strong relationship between the variability of individual song parameters and their potential importance in song recognition and the evaluation of male quality. The partial inconsistency of our results with the data of other authors may be due to different patterns of past and current selection on long‐distance and short‐distance acoustic signals.     

Wing-flick Signals in the Courtship of the African Cave Cricket,Phaeophilacris spectrum

The male of the African cave cricket Phaeophilacris spectrum (Saltatoria: Grylloidea: Phalangopsidae) possesses tegmina without stridulatory organs, and both females and males lack tympanal organs. Therefore acoustic communication in the usual sense, which is typical for most crickets, is absent in this species. However, adaptations of the wing articulation allow the males to flick their wings forward over their heads. During courtship these movements are performed in series of 4–5 wing-flicks at a rate of 8–12 Hz (called wing-flick series = WFS) which elicit low-frequency air movements. Such signals may have taken over the functional significance of an acoustic ‘courtship song’. A quantitative analysis of the cricket's behaviour showed that in terms of frequency and total duration, ‘wing-flick series’ and ‘rocking’ behaviour are the most prominent signals of the male's courtship display. Moreover, analysis of the spatial relationships between male and female demonstrates that the wing-flicking is directed towards the female. The response of a female to a wing-flicking, courting male seems mainly to be calmed down and to reach a passive, receptive state, necessary for subsequent copulation. Females confronted with a male's courtship display exhibited a significantly higher threshold to disturbing stimuli than uncourted ones.     

Field Cricket Species Differences in the Temporal Patterns of Long-Distance Mate Attraction Signals

We quantify variation in the temporal components of long‐distance mate attraction signals produced by a North American field cricket, Gryllus rubens Scudder. Total signaling time, trilling bout duration, and hourly bout number exhibit high repeatability within individuals. Extensive variation exists across individuals: some males never signal while others signal for several hours each night; of the signalers, average trilling bout duration ranges from <1 min to well over an hour; some males produce only one trilling bout in an evening while others produce three bouts every 2 h. Body size, weight, wing morphology, and condition do not appear to explain the variation. We compare the temporal signaling components of G. rubens with its sister species, G. texensis. Although G. rubens produce slightly more trills per hour with slightly shorter trilling bout durations, the temporal components of these long‐distance mate attraction signals are surprisingly similar across species.     

Female Mate Choice, Calling Song and Genetic Variance in the Cricket, Gryllodes sigillatus

Female preferences for song patterns of males of Gryllodes sigillatus and genetic variance of morphological traits correlated with them were analyzed. Females preferred short pulses associated with large males. The males’ thorax width, wing length and femur III length showed stronger relationship with the song pulse duration, whereas the relationship between pulse duration and wing width was not significant. Interestingly, this last trait was the only one that showed significant levels of genetic variance. Perhaps these results could be explained by the evolutionary response to sexual selection. Sexual selection could deplete the genetic variance in the male traits related to male‐mating success.     

On Interrelations between Temporal Parameters of the Calling Song of the Cricket Gryllus bimaculatus

Based on analysis of the temporal dynamics of parameters of the calling song in male crickets Gryllus bimaculatus, a conclusion has been made about the existence of a certain correlation between the number of pulses in chirps, on one hand, and chirp repetition periods and interchirp intervals, on the other hand. It is suggested that this correlation reflects a certain process running in the nervous system of a singing male with variable intensity that depends on both the external and the internal, including genetic, factors.     

Seasonality and Hormonal Control of Territorial Aggression in Female Song Sparrows (Passeriformes: Emberizidae: Melospiza melodia)

Male and female song sparrows perform similar aggressive behaviors including flights, wing-wave threat displays, and growls. Females very rarely sing, however. To investigate the seasonal variation and hormonal control of territorial aggression in females, we simulated female intrusions during the pre-breeding, breeding and post-molt seasons in the field. Circulating levels of testosterone, dihydrotestosterone, estradiol, progesterone and corticosterone in females experiencing simulated intrusion were compared to those of passively netted females matched for breeding stage. Female aggressive responses to female intrusion dropped from the pre-breeding to the post-molt seasons. Levels of circulating androgens were significantly higher in control females than in females experiencing a simulated intrusion. There were no significant differences in any of the other hormones measured. Although song sparrow female-female aggression appears to be behaviorally similar to male-male aggression, the seasonal variation and hormonal support of aggression differ between the sexes.     

Seasonal Variation in Female Response to Male Calling Song in the Field Cricket, Gryllus rubens

Conspicuous traits that make males attractive to females may make them vulnerable to predators. Females that approach conspicuous males may increase their risk of predation. This means that selection for reduced male conspicuousness in the presence of predators may be due to sexual selection resulting from altered female behavior in the face of increased predator risk. We examine this hypothesis in the field cricket, Gryllus rubens, in which male calling song attracts both conspecific females for mating and parasitoid flies (Ormia ochracea) which kill their hosts within a week. Female crickets are also parasitized by these flies as a result of associating with calling males. In northern Florida crickets that emerge in the spring are not subject to fly parasitism whereas autumn crickets encounter large numbers of flies. We predicted that autumn females should be less attracted to male song than spring females. We tested female response to male calls in a rectangular arena in which male calling song was broadcast from a speaker. Spring females readily approached the speaker but autumn females were less likely to approach and remain in the vicinity of the speaker. These results emphasize the importance of considering how risk affects the evolution of conspicuous male behavior both directly through its effect on the male and indirectly through its effect on female responses to males.     

Hormonal Control of the Teleost Ovary

The endocrine basis of gonadal development, reproductive processes,and many peculiarities related to reproduction in females ofthe highly diveisified teleosts can not yet be described satisfactorily.Although estrogens have been extracted from ovaries and peripheralblood of several species and various steroids were found tobe produced by ovarian tissue in vitro, there is an almost completelack of knowledge about their physiological role. It is beyond any doubt that hormones of the pituitary have amarked influence on ovarian maturation but many problems awaitfurther clarification. It is not yet clear whether gonadotropichormones might have a direct influence on certain traits ofbehavior in females. Biochemical work and a large number ofhistophysiological studies are at variance with regard to thequestion whether one or two gonadotropic hormones exist in teleosts.Technical difficulties (eg., shortage of hormonal material fromvarious sources, species specificity of gonadotropic hormone(s), widely scattered data from a large array of species withconsiderable differences in reproductive biology) hamper comparativeanalysis, Investigations on the hypothalamic control of endocrineevents are just in their beginning. The unique occurrence ofambisexual species in teleosts raises many questions which remainto be solved.     

No Effect of Body Size on the Frequency of Calling and Courtship Song in the Two-Spotted Cricket,Gryllus bimaculatus

The relationship between body size and vocalization parameters has been studied in many animal species. In insect species, however, the effect of body size on song frequency has remained unclear. Here we analyzed the effect of body size on the frequency spectra of mating songs produced by the two-spotted cricket, Gryllus bimaculatus. We recorded the calling songs and courtship songs of male crickets of different body sizes. The calling songs contained a frequency component that peaked at 5.7 kHz. On the other hand, courtship songs contained two frequency components that peaked at 5.8 and 14.7 kHz. The dominant frequency of each component in both the calling and courtship songs was constant regardless of body size. The size of the harp and mirror regions in the cricket forewings, which are the acoustic sources of the songs, correlated positively with body size. These findings suggest that the frequency contents of both the calling and courtship songs of the cricket are unaffected by whole body, harp, or mirror size.     

Hormonal Control of Meiosis in Starfishes

Development of starfish oocytes is blocked at the prophase stage of the first meiotic division. The resumption of meiotic divisions occurs under the effect of the maturation hormone 1-methyladenine (1-MeA), which binds to a specific receptor of the oocyte cell surface. New data in the literature on endocellular signal mechanisms taking part in conduction of the regulatory signal modulated by 1-MeA are adduced in the review. Data on the properties of the 1-MeA receptor are presented and mechanisms of biosynthesis of 1-MeA are considered. The main focus is on processes occurring in the oocyte during the first minutes after the impact of the hormone, before the destruction of the germinal vesicle. A hypothetical pattern of transduction of the hormonal signal is proposed.     

Photosensing and Processing of Sensory Signals in Halobacterim halobium

Halobacteria detect changes in light intensity by retinal proteins, the number and identity of which are not yet unequivocally established. The sensory receptors are different from those for light energy conversion. The cells having no preferred swimming direction spontaneously reverse about every 10 s. An oscillator model has been proposed to explain this periodicity. Depending on wavelength and sign, a stimulus leads either to one prolonged interval between two reversals, the attractant response, or to a shortened interval, the repellent response. Sensory signals generated by stimulation of P-565 and of P-370 are integrated at a common link. Signals from other receptors may be processed by separate links. The nature of the sensory signals is not known, but the membrane potential can be excluded as a candidate. On the basis of the oscillator hypothesis the output signals of the integration links act on the oscillator and thus shift the time at which it triggers a reversal of the flagellar motor. Experiments indicate that cGMP and calcium play antagonistic roles in the oscillatory activity. Reversible methylation of specific membrane proteins influences the time during which successive signals are integrated. This reaction is assumed to terminate the lifetime of the excitatory signals and thus to allow the system to adapt.     

Hormonal Control of Molting and Reproduction in Ticks

SYNOPSIS. Among ticks there are two developmental and threereproductive patterns that correlate with taxonomic groupings(Argasidae, prostriate and metastriate Ixodidae). Feeding isa prerequisite for molting; feeding and mating are necessaryfor reproduction in all except a few parthenogenetic species.Growth and development in ticks and other chelicerates appearto be controlled by molting hormones (ecdysteroids), as theyare in insects and crustaceans. Ecdysone and 20-hydroxyecdysoneappear to be present in most or all of the major cheliceratetaxa. Epidermis is the site of ecdysone production and fat bodythe site of 20-hydroxylation in the argasid Ornithodoros parkeri,as is probably the case in all ticks. Ecdysteroids influenceearly stages of spermatogenesis by stimulation of DNA synthesisin spermatocytes, but controls for later stages of meiosis areunknown. A polypeptide (12,000 daltons) from male genital accessoryglands stimulates capacitation (maturation) of spermatids intosperm at the time of spermatid transfer to females. Knowledgeof control of egg development and oviposition is incomplete.Stimuli from the synganglion are necessary for completion ofoogenesis and two synganglial factors have been proposed. AnEgg Development Stimulation Factor (EDSF) in O. parkeri is synthesizedand/or released three to six days after feeding. VitellogenesisInducing Factor (VIF) in O. moubata is synthesized and/ or releasedwithin one hour after feeding. The VIF is hypothesized to impactan unidentified tissue which in turn produces a Fat Body StimulationFactor (FSF) that stimulates fat body to synthesize vitellogenin(Vg). Roles of ecdysteroids and juvenile hormones during eggdevelopment and oviposition are unclear.     

AUXIN RESPONSE FACTOR 2 Intersects Hormonal Signals in the Regulation of Tomato Fruit Ripening

The involvement of ethylene in fruit ripening is well documented, though knowledge regarding the crosstalk between ethylene and other hormones in ripening is lacking. We discovered that AUXIN RESPONSE FACTOR 2A (ARF2A), a recognized auxin signaling component, functions in the control of ripening. ARF2A expression is ripening regulated and reduced in the rin, nor and nr ripening mutants. It is also responsive to exogenous application of ethylene, auxin and abscisic acid (ABA). Over-expressing ARF2A in tomato resulted in blotchy ripening in which certain fruit regions turn red and possess accelerated ripening. ARF2A over-expressing fruit displayed early ethylene emission and ethylene signaling inhibition delayed their ripening phenotype, suggesting ethylene dependency. Both green and red fruit regions showed the induction of ethylene signaling components and master regulators of ripening. Comprehensive hormone profiling revealed that altered ARF2A expression in fruit significantly modified abscisates, cytokinins and salicylic acid while gibberellic acid and auxin metabolites were unaffected. Silencing of ARF2A further validated these observations as reducing ARF2A expression let to retarded fruit ripening, parthenocarpy and a disturbed hormonal profile. Finally, we show that ARF2A both homodimerizes and interacts with the ABA STRESS RIPENING (ASR1) protein, suggesting that ASR1 might be linking ABA and ethylene-dependent ripening. These results revealed that ARF2A interconnects signals of ethylene and additional hormones to co-ordinate the capacity of fruit tissue to initiate the complex ripening process.     

The Hormonal Control of the Amphibian Ovary

The ultimate control of amphibian gonadal function rests withenvironmen tal factors mediated through the hypothalamus. Itappears that control of ovarian growth resides in the infundibularregion and ovulation in the preoptic area. For normal temporalrelationships between oocyte growth and ovulation to occur,an intact hypothalamo-pituitary complex is necessary. It isuncertain whether the several types of pituitary basophils considered,histologically as gonadotropin producing cells are in fact producingseparate LH and FSH like hormones. Perhaps the concensus indicatesa single hormone has both vitellogenic and ovulatory functions.This hormone stimulates estrogen synthesis and secretion bythe ovarian follicle cells, and this steroid causes oviductgrowth and the hepatic biosynthesis of vitellogenin, the majoryolk platelet precursor. Uptake of this lipoprotein from thecirculation and its conversion to the components of the plateletis mediated by the gonadotropin, the presence of which resultsin the establishment of a rapid micropinocytotic process atthe level of the oocyte surface and of a mechanism for crystallizationof the yolk. A sudden surge of pituitary hormone, when presentedto fully grown oocytes leads to their maturation and ovulation,and to oviducal jelly release in some species. The active hormoneis progestin in nature, again produced by the follicle cells. In this review the known factors involved in the hypothalamohypophysio ovarian axis are discussed together with some considerationof outstanding problemsand the possible relevance ot ovipantvand ovovivipanty in amphibians to the ovarian control foundin viviparous species.     

Gravity Influences Top-Down Signals in Visual Processing

Visual perception is not only based on incoming visual signals but also on information about a multimodal reference frame that incorporates vestibulo-proprioceptive input and motor signals. In addition, top-down modulation of visual processing has previously been demonstrated during cognitive operations including selective attention and working memory tasks. In the absence of a stable gravitational reference, the updating of salient stimuli becomes crucial for successful visuo-spatial behavior by humans in weightlessness. Here we found that visually-evoked potentials triggered by the image of a tunnel just prior to an impending 3D movement in a virtual navigation task were altered in weightlessness aboard the International Space Station, while those evoked by a classical 2D-checkerboard were not. Specifically, the analysis of event-related spectral perturbations and inter-trial phase coherency of these EEG signals recorded in the frontal and occipital areas showed that phase-locking of theta-alpha oscillations was suppressed in weightlessness, but only for the 3D tunnel image. Moreover, analysis of the phase of the coherency demonstrated the existence on Earth of a directional flux in the EEG signals from the frontal to the occipital areas mediating a top-down modulation during the presentation of the image of the 3D tunnel. In weightlessness, this fronto-occipital, top-down control was transformed into a diverging flux from the central areas toward the frontal and occipital areas. These results demonstrate that gravity-related sensory inputs modulate primary visual areas depending on the affordances of the visual scene.     

溶葡球菌酶前体及前体加工蛋白酶的生成控制和纯化

 为深入探讨溶葡球菌酶前体加工转化为成熟的溶葡球菌酶的机制,本文通过条件控制分别从Staphylococcus simulans的培养液中获得了溶葡球菌酶前体和它的加工蛋白酶,并分别通过HPLC和Affi-Gel 501亲和层析对它们进行了纯化,根据聚丙烯酰胺凝胶电泳和凝胶等电聚焦电泳,表明二者已基本上达到均一的程度。在此基础上,又进行了溶葡球菌酶前体的体外加工转化实验。     

Hormonal Control of Tumor Formation in Radish

The role of phytohormones in genetic tumor formation on radish crop-roots was investigated using the collection of inbred Raphanus sativus lines as a model system. The genetic analysis showed that the trait <<tumor formation>> was recessive and monogenic in some crossings. The spectrum of main phytohormones in tumor and non-tumor radish lines has shown that at the initiation of tumor formation (30 days old plants) the amounts of main cytokinins in the lower part of plants from the tumor line were dramatically increased. The transformation of the non-tumor line by the ipt gene of Agrobacterium tumefaciens resulted in tumor formation in plants of the T₁ progeny. We propose that increasing the cytokinin/auxin ratio may lead to tumor formation on radish crop roots.     

Hormonal Control of Molting in Decapod Crustacea

The involvement of the molting hormone, 20-hydroxyecdysone,in the mediation of molting in decapod crustaceans is brieflyreviewed. Aspects of the secretion and metabolism of its precursor,ecdysone, are discussed. Experiments are described that demonstratethe presence of a molt-inhibiting hormone (MIH) in the sinusglands of juvenile lobsters (Homarus americanus). Assays forMIH include measurement of the molt interval and radioimmunoassayof circulating titers of ecdysteroids in eyestalk-ablated lobsters.This latter assay indicates that sinus gland extracts significantlydecrease the concentration of circulating ecdysteroids 24 hrafter injection. Data are also presented on the circulatingtiters of ecdysteroids during multiple molt cycles of lobstersfollowing eyestalk ablation. These data indicate that theremust be another factor that ultimately regulates the circulatinglevels of the molting hormone.