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At least 19 recordsLinked to original sources
PubMed1992

Behavioral coupling in tettigoniid hybrids (Orthoptera).

Studies of the mating behavior of male and female F1 hybrids between closely related taxa can provide information concerning the genetic control of characters that play a major role in speciation. Orthoptera have been used previously for such studies. Hybrid crickets show behaviors which are broadly intermediate to the parentals but hybrid grasshoppers may retain parental behavior patterns. This study examines the behavior of hybrid Ephippiger ephippiger bushcrickets, the third major orthopteran group. The differences in male song and female preference are probably both mainly additive and male song differences not sex linked. Thus, given a choice, hybrid females would prefer to mate with hybrid males, an example of "behavioral coupling." The evolutionary inferences which can be drawn from studies of F1 hybrids between closely related taxa are discussed.

Animals↗
PubMed1989

Orthoptera as intermediate hosts of Staphylocystis furcata (Stieda, 1862) (Cestoda: Hymenolepididae).

Cysticercoids of Staphylocystis furcata (Stieda, 1962), the adults of which parasitize the shrews (Soricidae), were found in the thoracic and abdominal cavities of orthopterous insects (Orthoptera, Acridioidea) belonging to five species: Chorthippus apricarius (L.), Chorthippus paralellus (Zett.), Omocestus viridulus (L.), Chrysochraon brachypterus (Ocsk.), and Chrysochraon dispar (Germ.). The cysticercoids are described and their incidence in both sexes of the examined intermediate hosts is compared.

Animals↗
PubMed1991

Ultrasonic startle behavior in bushcrickets (Orthoptera; Tettigoniidae).

1. In the present work, we show that in flight, bushcrickets not previously known to respond to ultrasound alter their flight course in response to ultrasonic stimuli. Such stimuli elicit in flying Neoconocephalus ensiger an extension of the front and middle legs along the body and a rapid closure of all 4 wings (Fig. 1). This is a short latency acoustic startle response to ultrasound, consistent with acoustic startle responses of other insects. 2. The percentage of trials on which acoustic startle responses were elicited was maximum (90%) for sound frequencies ranging from 25 to at least 60 kHz. No acoustic startle response was observed at frequencies of 5 or 10 kHz (Fig. 2). The threshold for the response was roughly 76 dB between 25 to 60 kHz (Fig. 2) and the behavioral latency was 45 ms (Fig. 3). Recordings from flight muscles show that they cease discharging during the acoustic startle response (Fig. 4). 3. The characteristics of the acoustic startle response match those of an auditory interneuron called the T-neuron. The frequency sensitivity of this neuron is greatest for sound frequencies ranging from 13 to 60 kHz (Fig. 6). Moreover, we found that the neuron produces many more spikes to ultrasound (30 kHz) of increasing intensities than to a conspecific communication sound, whose dominant frequency is 14 kHz (Fig. 7).

Acoustic Stimulation↗
PubMed1979

Length heterogeneity of amplified circular rDNA molecules in oocytes of the house cricket Acheta domesticus (Orthoptera: Gryllidae).

Amplification of the genes coding for rRNA occurs in the oocytes of a wide variety of organisms. The amplification process appears to be mediated through a rolling-circle mechanism. The approximate molecular weight of the smallest rDNA circles is equivalent to the estimated combined molecular weight of DNA which codes for a single ribosomal RNA precursor molecule and an associated non-transcribed spacer DNA sequence. RNA-DNA hybridization studies carried out on oocytes of the house cricket, Acheta domesticus, suggest that DNA coding for rRNA accounts for only a small fraction of the rDNA satellite, all of which is amplified in the oocyte. In order to test the possibility that the remainder of the amplified rDNA represents spacer and to determine whether a rolling-circle mechanism might also be involved in amplification in A. domesticus oocytes, rDNA was isolated from ovaries of A. domesticus and spread for electron microscopy. A large proportion of the rDNA isolated from ovaries is circular, while main-band DNA and rDNA prepared from other tissues demonstrates few if any circles. The mean size of the smallest rDNA circles is approximately 8 times longer than the length estimated for DNA which codes for 18S and 28 S rRNA. Denaturation mapping shows the rDNA circles to contain two major readily denaturing regions located about equidistant from one another on the circle. Each readily denaturing region accounts for 4--6% of the total DNA in the circle. The fact that only 12% of the average molecule is required to code for A. domesticus 18S and 28S rRNA is consistent with the hybridization data. Considerable size heterogeneity exists in the length of the smallest class of rDNA molecules. In the rDNA of other species such heterogeneity has been shown to reside in the non-transcribed spacer.

Animals↗
PubMed1986

Analysis of a large nontranscribed spacer in the ribosomal DNA of the house cricket, Acheta domesticus (Orthoptera:Gryllidae).

An analysis of a 29-kilobase nontranscribed spacer fragment in the ribosomal DNA (rDNA) of the house cricket, Acheta domesticus, revealed a highly repetitious structure. A total of eight EcoRI repeats of three different size classes measuring 259, 420, and 508 base pairs (bp) was mapped to a region 2 kilobases (kb) from the 18 S coding region. The repeats were oriented in a nonrandom manner and had sequences homologous to DNA located immediately adjacent to the repetitive array. DNA sequence analysis showed that the repetitive region was composed of smaller direct repeats 66, 67, and 383 bp in length. There was minor length heterogeneity of the chromosomal restriction fragments containing the entire array, indicating that a variable number of EcoRI repeats is a minor contributor to the total repeat-unit length heterogeneity. Immediately upstream from the EcoRI array there is a 17-kb region composed of 50 to 60 subrepeat elements recognized by a variety of restriction endonucleases. A subcloned SmaI repeat from the array was not homologous to any other part of the rDNA repeat unit or other chromosomal DNA. There was little length heterogeneity in restriction fragments containing the chromosomal 17-kb repetitions region. Immediately upstream from the 17-Kb region there is a 4.1-kb segment with sequences homologous to the EcoRI repeats.

Animals↗
PubMed1990

The delta 12-desaturase from the house cricket, Acheta domesticus (Orthoptera: Gryllidae): characterization and form of the substrate.

A novel delta 12-desaturase from animals, which converts oleic acid (18:1n-9) to linoleic acid (18:2n-6), was characterized in the house cricket, Acheta domesticus. The delta 12-desaturase product, linoleic acid, was determined by silver nitrate thin-layer chromatography, radio-gas-liquid chromatography and radio-high-performance liquid chromatography with the latter being used for routine analyses. Enzyme activity was located in the microsomal fraction of whole insect homogenates. NADPH or NADH was required for activity, with NADPH being the more efficient electron donor. In short incubation times with oleoyl-CoA as substrate, the highest amount of product, linoleic acid, was found as linoleoyl-CoA. With longer incubation periods, most of the linoleic acid was recovered in the polar lipid fraction containing phospholipid. Preincubation of the microsomal preparation in the absence of NADPH, which allowed 90% of the oleoyl moiety to be transacylated into complex lipid, resulted in no detectable desaturation upon addition of NADPH. These data indicate that the oleic acid moiety used as substrate was in the form of a CoA derivative and not in the form of a phospholipid, as it is for the plant delta 12-desaturase. This is the first characterization of a delta 12-desaturase from an animal system and the first report of a delta 12-desaturase that uses oleoyl-CoA as substrate.

Animals↗
PubMed1990

Ovaries and regulation of juvenile hormone titer in Acheta domesticus L. (Orthoptera).

A study was performed on females Acheta domesticus to examine the effects of various experimental conditions on the ovarian physiology. Using a radioimmunoassay to determine juvenile hormone (JH) titers as well as in vitro JH biosynthesis, we observed that retention of mature follicles in egg-retaining females, i.e., virgins or mated females not provided an egg-laying substrate, inhibits JH production and consequently oocyte development. Mating in intact as well as ovariectomized females does not affect corpora allata activity. It is only when mating is associated with egg laying that JH biosynthesis and hemolymph titers increased and oocyte development and fecundity are stimulated. Despite lower JH biosynthesis, ovariectomized females present enlarged corpora allata and the levels of JH observed in their hemolymph were intermediate between those of intact egg-laying and virgin females. In intact females, the hemolymph JH titers as well as the JH esterase activities were related to ovarian development. JH esterase activity was very high in ovariectomized animals. Several factors involved in ovarian development of A. domesticus are discussed.

Animals↗
PubMed1992

Insect sex chromosomes, XI. 3H-TdR induces random aberrations in the X chromosome(s) of Gryllotalpa fossor (Orthoptera).

The pattern of titrated thymidine (3H-TdR), a direct precursor of DNA, induced aberrations on the X chromosome of Gryllotalpa fossor was examined. 3H-TdR produced aberrations randomly distributed over the entire length of the X chromosome; breaks were observed in both the eu- and the heterochromatic arms of the X chromosome in both the sexes. Since the eu- and the heterochromatic arms cannot be distinguished cytologically in this insect, the presence of aberrations on both arms of the same X chromosome in the male and damage to both X chromosomes in the female indicate that both euchromatic and heterochromatic regions (facultative or constitutive) are equally liable to aberrations induced by H-TdR. This is in contrast to the non-random induction of aberrations by 3H-UdR, which causes chromosome damage due to the proximity of the labeled RNA to the DNA template during transcription.

Animals↗
PubMed1989

Inversion polymorphisms in Trimerotropis pallidipennis (Orthoptera): clinical variation along an altitudinal gradient.

Six populations of Trimerotropis pallidipennis located along an altitudinal gradient in the Antinaco-Los Colorados valley (La Rioja, Argentina), were cytologically analysed. The male karyotype consists of 23 chromosomes (22 + XO) with three long pairs submetacentric, the X-chromosome metacentric and the remaining ones basically acrocentric. Populations from La Rioja were polymorphic for seven pericentric inversions. Correlations between chromosome frequencies and altitude were statistically tested. In most cases, variables were either positively or negatively related in a significant fashion. As a consequence, mean populational heterozygosis (measured as the mean number of heteromorphic bivalents per individual per population) was also positively correlated with altitude. These results suggest that altitude (or other correlated environmental variable) may exert a differential selective pressure on coadapted gene blocks in the mutually inverted sequences. The possible relation of these results with the central-marginal model is discussed.

Altitude↗
PubMed1990

Localization of the circadian pacemakers of Hemideina thoracica (Orthoptera; Stenopelmatidae).

The location of the circadian pacemakers of the orthopteran Hemideina thoracica (White) has been investigated through observation of the effects of surgical removal of brain tissues (principally optic lobes and tracts) on free-running and entrained locomotor rhythms. Bilobectomy and severance of optic tracts invariably resulted in arrhythmicity, whereas rhythmicity was sustained following unilateral lobectomy, generally with increases in the free-running period (FRP) and decreases in both the active-phase lengths and activity-to-rest ratios of the rhythm. Bilobectomized subjects could be entrained by temperature cycles, but exhibited no transients or residual rhythmicity, indicating that temperature brought about a direct response or masking effect. These results support the hypothesis that the circadian locomotor pacemakers of Hemideina are located within each optic lobe, and that there are no extraoptic centers for the control of the timing of locomotor activity. Although confirmation of the pacemaker role of the optic lobes requires transplantation of the tissues, the conclusion may be drawn by inference from other studies (e.g., Leucophaea maderae--Page, 1983; Gryllus bimaculatus--Tomioka and Chiba, 1986). Light entrainment continued after surgical binding and blackening of the compound eyes and ocelli, supporting the view that direct illumination of neural tissue through the cuticle may be one possible pathway for light entrainment.

Animals↗
PubMed1990

Lectin binding to the egg envelopes in Eyprepocnemis plorans (Charp.) (Orthoptera, Acrididae).

The distribution of glycoconjugates in the egg envelopes of Eyprepocnemis plorans was investigated using various FITC-conjugated lectins. In the epichorion, the lectins ConA, SBA and WGA each have particular binding patterns, while TPA binding is confined to its deepest regions only. The glycoconjugates of the micropylar wall present different characteristics from those of the surrounding chorion. The vitelline coat shows a marked binding for WGA and TPA only; below the inner micropylar openings, this binding pattern is uniform over the whole extent of the coat and therefore it is not possible to identify specific binding sites for these two lectins. Contrary to what has been observed in some other insect species, the vitelline coat does not seem to be involved in the structural organization of the mycropyles.

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