Developmental changes in fatty acid biosynthesis and composition in the house cricket,Acheta domesticus

Incorporation of [1-¹⁴C] acetate into various phospholipid and triacylglycerol fatty acids showed cyclic fluctuations in fatty acid biosynthesis that were similar for all of the major fatty acids in both male and female house crickets, Acheta domesticus, during development. All three stadia showed low levels of biosynthesis near ecdysis followed by increased synthesis to a peak at midstadium. In the phospholipid fraction, the incorporation of newly synthesized saturated fatty acids, 16:0 and 18:0, predominated near ecdysis, while at midstadium linoleic acid was the most actively synthesized fatty acid. In the triacylglycerol fraction, 18:0 and 18:1 predominated throughout the entire stadium. In contrast to the large fluctuations in fatty acid biosynthesis, the fatty acid compositions of the phospholipid and triacylglycerol fractions did not change within a stadium. However, significant differences were demonstrated between the stages and were associated primarily with differences between nymphal and adult stadia. Males and females differed in the proportions of 16:0 and 18:2 incorporated into phospholipids with females showing a greater proportion of 18:2 and a corresponding smaller proportion of 16:0 than males. The greater proportion of linoleic acid in females and in adults in general compared to nymphs and the predominance of the incorporation of newly synthesized linoleic acid into the phospholipid fraction of all stadia are consistent with the importance of this fatty acid in a number of biological roles.     

Amino acid composition of sperm histones in the house cricket Acheta domesticus.

Histones were isolated from late spermatids and spermatozoa of the house cricket Acheta domesticus, and the individual histone fractions were separated by electrophoresis on polyacrylamide-urea gels. The stained gels were cut so as to isolate the different histone fractions, and the amino acid compositions were determined using the technique of Houston (Houston, L.L.: Anal. Biochem. 44, 81-88 (1971). Five of the histones had amino acid compositions resembling those for the histones of calf thymus and were thus identified as fractions F1, F3, F2a2, F2b, and F2al. Another protein (SH) located exclusively in the late spermatids and spermatozoa was found to be basic and histone-like. It is a protein containing relatively high amounts of arginine (12.6%) and low amounts of lysine (7.6%), and, as a result, it has a low ratio of lysine-arginine (0.6). Other noteworthy features are its high contents of serine, glutamic acid, and glycine. It is arginine rich histone and in this regard resembles other such proteins, but it does contain unique features which distinguish it from all previously described histones.     

Neuronal pathways from the dorsal acelli of the house cricket,Acheta domesticus

Each ocellar nerve in the house cricket Acheta domesticus contains giant nerve fibers of 10-15 μ diameter, characterized in Golgi Cox preparations by a single row of short collaterals which runs along nearly the entire length of a fiber. Numerous long collaterals are given off by thin fibers in the ocellar nerve; medium-size fibers give off relatively few collaterals. The lateral ocellar tracts extend posteriorly through the dorsal protocerebrum, crossing the protocerebral bridge dorsally. The smaller median ocellar tract runs more ventrally through the pars intercerebralis; posterior to the bridge its fibers turn out toward the lateral nerves. Golgi and cobalt preparations reveal branching of giant and mediu_-size ocellar fibers posterior to the bridge at two levels, forming bilateral regions of ocellar neuropile. No ocellar processes appear to be given off to the corpora pedunculata, centra! body, nervi corporis cardiaci, antenna! lobes, or circumesophageal connectives; it is uncertain whether ocellar collaterals extend into the protocerebral bridge or optic lobes. Cell bodies of giant and medium-sized fibers are located in the pars intercerebralis.     

The energetic costs of fighting in the house cricket, Acheta domesticus L

The cost of performing an agonistic behavior, or tactic, willhave consequences for an individual's rate of cost accrual,the tactic's evolutionary stability if used as an assessmentsignal, and its pattern of use in the behavioral choreographyof a contest. Few studies have attempted to quantify the costsof fighting, particularly with regard to energy expenditure.Flow-through respirometry revealed that house cricket malescan expend energy at relatively high rates when fighting (morethan eight times resting levels) depending on the particulartactic performed. Acoustic signalling (stridulation) constitutedthe least costly of seven measured agonistic tactics, whilewrestling with an opponent, the most energetically costly tactic,consumed oxygen at a net rate more than 40 times that of stridulation.Low-cost tactics are used by opponents more frequently thanmore costly tactics, providing evidence for an escalating tacticalconvention based on energetic costs. The moderate energeticcost of some tactics suggests they may function as reliablesignals in the assessment of wrestling ability. Net energy costsper contest increased linearly with contest duration for bothcontest winners and losers, but winners tended to expend moreenergy per contest than losers. The likely fitness effects ofenergy expended while fighting are discussed. The results ofthis study indicate that energy expenditure is an importantcost shaping contest strategies in Acheta domesticus     

An advantage for young sperm in the house cricket Acheta domesticus

We show that males of the house cricket Acheta domesticus regularly expel sperm packages (spermatophores) independently of copulation and at a rate that is not affected by the presence of females. We then show for the first time that the age of sperm affects their likelihood of being stored by females after copulation; younger sperm were overrepresented in the female sperm storage organ and therefore in the sperm population used for fertilization. Our results suggest that the reproductive success of males may increase if they deliver ejaculates with young sperm, and the results may explain why the males of several species are regularly observed to discard ejaculates. Our results also suggest that phenomena such as female multiple mating, paternity bias, and/or exaggerated ejaculate sizes may be related to the advantage both genders gain by using young sperm.     

Role of juvenile hormone metabolism during embryogenesis of the house cricket,Acheta domesticus

The duration of embryogenesis was 9.5 days for house crickets, Acheta domesticus (L.), reared at 35°C. The major route of juvenile hormone (JH) metabolism was ester hydrolysis. The level of α-naphthyl acetate (α-NA) esterase activity per mg wet weight remained relatively constant throughout embryogenesis and was similar to that of eggs dissected from the oviducts. JH esterase activity per mg wet weight was highest in the dissected and day-1 eggs, declined to one-third of this peak activity by day 5, and then remained unchanged through hatching. Two populations of esterases (130,000 and > 200,000 in molecular weight) which metabolized JH and α-NA were resolved in day-1 eggs by gel filtration chromatography. Specific JH esterase appeared by day 4 with a molecular weight of 200,000. Correlative evidence is presented from other insect species that supports a functional role for JH metabolism during embryo development.     

Quantitative genetics of immune function and body size in the house cricket,Acheta domesticus

Female house crickets are attracted to male calling song containing a relatively high number of syllables per ‘chirp’, which tends to be produced by large males. In a previous study, we showed that this song characteristic is also positively and independently correlated with haemocyte load, an important determinant of the ability to produce an encapsulation response in insects. Females will therefore tend to select males with high encapsulation ability (and large body size) as mates. The present study demonstrates that variation in haemocyte load and body size, together with a second parameter of immune function (the ability to encapsulate a synthetic substrate), is heritable in the same population. Moreover, all three traits are shown to be positively genetically correlated. In favouring males that produce calling song with the preferred characteristics, females should therefore also tend to produce larger offspring with a greater ability to produce an encapsulation response.     

Regional variation in cuticular hydrocarbon composition in the common house cricket,Acheta domesticus

• 1.1. The hydrocarbon composition of different cuticular regions (pronotum, legs, abdominal tergites and sternites, pleural membrane) was determined for adult female crickets (Acheta domesticus).
• 2.2. Hydrocarbon groups included n-alkanes, 2-methylalkanes, long-chain internally branched monomethyl- and dimethyalkanes, n-alkenes, 2-methylalkenes and alkadienes.
• 3.3. Saturated hydrocarbons were more abundant than unsaturated hydrocarbons and branched saturates more abundant than n-alkanes in all regions of the cuticle examined.
• 4.4. Except for a higher percentage of n-alkanes in the pleural membrane (soft cuticle), little difference was noted in compositional patterns or relative amounts of individual molecules from the different cuticular regions.

     

Ultrastructure of the corpus cardiacum and corpus allatum of the house cricket Acheta domesticus

Summary The ultrastructure of the corpus cardiacum (CC) and corpus allatum (CA) of the house cricket, Acheta domesticus, is described. Axon profiles within the CC contain neurosecretory granules 160–350 nm in diameter which are indistinguishable from those found in type I neurosecretory cells of the pars intercerebralis and in the nervus corporis cardiaci I. The CC itself contains two cell types: intrinsic neurosecretory cells and glial cells. Intrinsic NSC cytoplasm contains Golgi bodies and electron dense neurosecretory granules 160–350 nm in diameter. Synaptoid configurations with 20–50 nm diameter electron lucent vesicles were observed within axon profiles of the CC. The structure of the CA is relatively uniform with one cell type predominating. Typical CA cells possess large nucleoli, active Golgi complexes, numerous mitochondria, and occassional microtubules. Groups of dark staining cells scattered throughout the CA of some animals were interpreted as evidence of cellular death.This work was done while JTB was supported by USPHS Training Grant HD-0266 from NICHDI wish to express my thanks to Dr. Richard A. Cloney for sharing his expertise in electron microscopy     

Temperature and the energetics of development in the house cricket (Acheta domesticus)

The influence of rearing temperature on the energetics of development was investigated in house crickets (Acheta domesticus). Crickets raised at 25 degrees C grew slower (0.51 mg d(-1), dry mass basis) and took longer to develop (119 d) but obtained a greater adult body mass (61 mg, dry mass) than crickets reared at 28 degrees C (0.99 mg d(-1), 49 d, 48 mg). Total metabolic energy consumed during development at 25 degrees C (1351 J) was twice that at 28 degrees C (580 J) primarily because of the longer development period, and as a consequence the specific net cost of growth was much greater for crickets reared at 25 degrees C (22.1 kJ g(-1)) than 28 degrees C (11.9 kJ g(-1)).     

The distribution and relative potency of diuretic peptides in the house cricket, Acheta domesticus

ABSTRACT Dose-response curves are presented for the diuretic activity in aqueous extracts of brain, retrocerebral complex, and ventral nerve cord ganglia from Acheta domesticus . Diuretic activity is highest in extracts of brain and corpora cardiaca. In comparison with such extracts, those of the suboesophageal ganglia and thoracic ganglia I-III produce truncated responses, whilst abdominal ganglia 1–4 show evidence of an inhibition of the diuretic response at high doses. ED₅₀ values, obtained from Hill plots, are similar for extracts of brain, corpora cardiaca, corpora allata, and abdominal ganglia, but are 3–4 times higher for extracts of suboesophageal and thoracic ganglia.
Separation of aqueous extracts of corpora cardiaca by reversed-phase HPLC yields a number of fractions which stimulate fluid secretion in isolated tubules. Diuretic activity in these fractions is destroyed by treatment with Pronase E, and on this basis is identified as peptidic. In general, diuretic activity is found in the same RP-HPLC fractions prepared from aqueous extracts of brain, suboesophageal ganglia, thoracic ganglia I-III, and abdominal ganglia 1–4.     

Dietary sodium, potassium and calcium requirements of the house cricket, Acheta domesticus (L.).

1. The optimal level of sodium in an artificial diet for the house cricket was found to be 1126 ppm, of potassium 6487 ppm and of calcium 1366 ppm. 2. The revised salt mixture for the house cricket is 68.02 g NaCl, 120.00 g KCl, 310.00 g KH2PO4, 37.65 g CaHPO4, 53.34 g CaCO3, 90.50 g MgSO4.7H2O, 14.70 g FePO4.4H2O, 0.23 g MnSO4.H2O, 0.55 g ZnCO3 and 0.72 g CnSO4 in a total of 695.71 g salts.     

Stimulation of fluid secretion by single isolated Malpighian tubules of the house cricket, Acheta domesticus

Abstract. Fluid secretion by single isolated Malpighian tubules of Acheta domesticus (L.) is stimulated by aqueous extracts of nervous and neuroendocrine tissues from the cricket. Diuretic activity, expressed as the increase in rate of secretion per microgram tissue protein (pl/mm/min/ug protein), is highest in the CA and CC.
The response to aqueous CC extracts is dose-dependent. The maximum increase in secretion rate is 300–350 pl/mm/min and the ED_max and ED₅₀ are 0.1–0.2 and 0.02–0.03 gland pairs respectively.
The diuretic activity in the CC is retained after 5min at 95C, and is freely soluble in 80% methanol. Diuretic activity is, however, greatly reduced after prolonged heating or after treatment with either pronase or chymotrypsin. It is conluded that the diuretic factor(s) is a low molecular weight peptide. A loss of activity after incubation with pyroglutamate amino peptidase suggests that some active peptides present are N-terminally blocked.
The diuretic activity of crude aqueous CC extracts is rapidly lost on standing at room temperature. This is partly prevented by precipitation of protein enzymes by either heat treatment or extraction in methanol.
Synthetic vertebrate and insect neuropeptides are generally low in activity increasing fluid secretion by no more than 60pl/mm/min. However, extracts of neuroendocrine tissues from a wide range of insect species are potent stimulants of tubule secretion. Various biogenic amines were tested and have little effect on fluid secretion; thus they cannot contribute greatly to the response of cricket tubules to aqueous tissue extracts.     

Mechanisms of calcium sequestration by isolated Malpighian tubules of the house cricket Acheta domesticus

Hemolymph calcium homeostasis in insects is achieved by the Malpighian tubules, primarily by sequestering excess Ca²⁺ within internal calcium stores (Ca‐rich granules) most often located within type I (principal) tubule cells. Using both the scanning ion‐selective electrode technique and the Ramsay secretion assay this study provides the first measurements of basolateral and transepithelial Ca²⁺ fluxes across the Malpighian tubules of an Orthopteran insect, the house cricket Acheta domesticus. Ca²⁺ transport was specific to midtubule segments, where 97% of the Ca²⁺ entering the tubule is sequestered within intracellular calcium stores and the remaining 3% is secreted into the lumen. Antagonists of voltage‐gated (L‐type) calcium channels decreased Ca²⁺ influx ≥fivefold in adenosine 3′,5′‐cyclic monophosphate (cAMP)‐stimulated tubules, suggesting basolateral Ca²⁺ influx is facilitated by voltage‐gated Ca²⁺ channels. Increasing fluid secretion through manipulation of intracellular levels of cAMP or Ca²⁺ had opposite effects on tubule Ca²⁺ transport. The adenylyl cyclase‐cAMP‐PKA pathway promotes Ca²⁺ sequestration whereas both 5‐hydroxytryptamine and thapsigargin inhibited sequestration. Our results suggest that the midtubules of Acheta domesticus are dynamic calcium stores, which maintain hemolymph calcium concentration by manipulating rates of Ca²⁺ sequestration through stimulatory (cAMP) and inhibitory (Ca²⁺) regulatory pathways.     

Interactions between social factors and ovarian development in the European house cricket Acheta domesticus

Several endocrine-mediated processes in insects are influenced by environmental factors including the density and sex ratio of populations. Effects of grouping on total egg production and rate of vitellogenic ovary development were assessed in virgin Acheta domesticus (L.). Females midway through their last nymphal instar were isolated from a stock population of adults and nymphs of both sexes and maintained in groups or as isolates at 26–27°C, 70% relative humidity, on a 12L-12D photoperiod. The number of fully grown oocytes produced during the first 18 days of adult life was lower for animals in groups of 10 or 15 than for isolates, but antennectomy abolished this group effect. By contrast, terminal and penultimate oocyte length and ovary dry weight were greater in 5-day-old - pairs than in isolates. The presence of mature males during the first 21 days of adult life did not affect total egg production. Whether these group effects on cricket ovary development are mediated by the endocrine system is not yet known.

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Interaction entre les facteurs sociaux et le développement ovarien d'Acheta domesticus

Résumé L'étude a examiné les effets de groupement sur la production d'oeufs et sur la vitesse de la vitellogenèse chez les femelles vierges d'Acheta domesticus. Des femelles à la moitié de leur dernier stade larvaire, isolées d'une population adulte de base, et des nymphes des deux sexes ont été conservées en groupes ou isolées dans des récipients en plastique de 150 mm de diamètre et de 25 mm de hauteur à 26–27°C, 70% d'humidité relative et avec une photopériode de 12/12. La production totale des oeufs mûrs formés pendant les 18 premiers jours de vie imaginale était plus faible pour les animaux en groupes de 10 ou 15 que pour ceux qui étaient isolés, mais l'antennotectomie a éliminé cet effet de groupe. Au contraire, la longueur des derniers et avant-derniers ovocytes et le poids sec des ovaires étaient supérieurs pour les paires de 2 femelles de 5 jours que chez les individus isolés. La présence de mâles mûrs pendant les 21 premiers jours de vie imaginale n'a pas eu d'effet sur la production totale d'oeufs. L'hypothèse avancée est que ces effets de groupe (négatifs et positifs) sur le développement des ovaires d'Acheta domesticus ont reflété respectivement des accélérations et ralentissements de la vitellogenèse. La dépendance de l'induction de la vitellogenèse chez Acheta domesticus par les hormones juvéniles est connue (Benford, 1983) ainsi que les changements dans la quantité de produits neurosécréteurs, susceptibles d'être colorés dans la pars intercerebralis au cours du cycle reproductif (Bradley et Simpson, 1981). Nous ne savons pas si ces effets de groupement sur le développement des ovaires de grillon sont médiatisés par le système endocrine.