The effect of digging on development of adult characters in blowflies Calliphora erythrocephala

Digging delays expansion after emergence of adult Calliphora. If flies are kept digging for 12 to 14 hr they lose the capacity to expand and, if they are then reared for 10 days, do not develop the normal adult corpus allatum, ovaries, and cuticle. In particular, ultrastructural examination of the resilin tendon of the pleurotergal muscle shows that development is arrested at a stage similar to that in the late pharate adult but the resilin is not cross-linked. It is suggested that bursicon release is irreversibly inhibited in flies that fail to expand normally.     

The relationship between age,acclimatization temperature,and heat death point in adult Calliphora erythrocephala

The heat resistance of adult Calliphora erythrocephala declines after eclosion and its rate of loss is dependent upon the temperature at which the adult is maintained. At 29°C the decline was complete in 5 days; at 24, 19, and 15°C it was complete in 10 days; at 10°C it was complete in 30 days; and at 5°C it was not complete even after 73 days. Physiological acclimatization in the adult stage was only observed at temperatures above 32°C, when an increase in heat resistance was superimposed upon the age-dependent decline.     

Effects of ecdysone on the in vivo growth of wing disks of Calliphora erythrocephala

The normal growth of wing disks is compared with the growth of disks from larvae surgically deprived of ring glands at 5 or 6 days and later unable to form a puparium. During the third instar, the growth of wing disks is constant. It seems to slow down after puparium formation. Twelve days after the ablation of the ring gland, the volume of the wing disks is no different from the volume of the wing disks for 6-day-old larvae. Ecdysone is needed for the growth of imaginal wing disks but the ecdysone peak does not accelerate growth.     

Membrane potential of the corpus cardiacum neurosecretory cells of the blowfly, Calliphora erythrocephala

The corpus cardiacum neurosecretory cells (c.n.c.) of Calliphora are unipolar cells with slender projections (axonal length: 50 to 110 μ; diameter: 0·25 to 1·75 μ).The cell body, where production of neurosecretory material occurs, is electrically inexcitable (resting potential about 36 mV, inside negative), whereas the axon—responsible for controlled neurohormone release—is excitable. Spike potentials with a duration of 3 to 7 msec occur in volleys the number and duration of which are supposed to determine the amount of secretion released. Electrical activity may be stimulated via the brain. Resting and action potentials are compared with recordings from other cell types of the blowfly.     

Effects of Weismann ring gland on RNA synthesis in imaginal wing disks of Calliphora erythrocephala

Imaginal wing disks of Calliphora erythrocephala have been studied in normal animals and in permanent larvae surgically deprived of the ring gland. By the end of larval life, uridine incorporation in the nuclear RNA and the ribosomal RNA increases for a brief period. This phenomenon does not occur in permanent larvae. A quantitative study suggests that renewal of a part of the ribosomal RNA might precede wing evagination.     

Threshold and receptor reserve in the action of 5-hydroxytryptamine on the salivary glands of Calliphora erythrocephala

The interrelationships of 5-HT receptors and the increased fluid secretion by isolated salivary glands of Calliphora have been studied using pharmacological techniques. Removal of the 5-OH group (tryptamine) or displacement to position 6 (6-HT) results in a decrease in potency but no change in intrinsic activity of the hormone whereas altering the ethyl amine side chain (5-OH tryptophan) results in a decrease in both potency and intrinsic activity. Removal of the 5-OH group and alteration of the side chain (gramine and tryptophan) results in a total loss of activity. Gramine and tryptophan behave as competitive antagonists of 5-HT.Prostaglandin E₁ (PGE₁) was found to be a non-competitive inhibitor of 5-OH tryptophan and theophylline whereas the response to 5-HT and cyclic AMP was only slightly diminished indicating a ‘receptor reserve’ for 5-HT.Saturating concentrations of gramine and tryptophan potentiate theophylline revealing a ‘threshold’ for the mediation of the response. It is concluded that 5-HT derivatives are capable of producing graded effects on adenyl cyclase both above and below the range of enzyme activity which evokes graded changes in fluid secretion.     

Increase in acid phosphatase activity in the fat body during larval and pharate pupal development in Calliphora erythrocephala

Biochemical evidence was obtained for an increase in acid phosphatase activity in the larval fat body of Calliphora erythrocephala during larval and pharate pupal instars. This observation is in conflict with published data indicating a decreasing enzyme activity in late third stage larvae. Centrifugation and filtration studies showed that the pH of the homogenisation medium has a strong influence on the solubilisation of acid phosphatase and its distribution in homogenate components. Differences in biochemical techniques including the pH value may explain the discrepancy between the published results and the present findings.The observed increase in acid phosphatase activity is related to the activity of the lysosomal system in the period immediately preceding pupal-adult apolysis.     

Hormone mediated induction of acid phosphatase activity in the fat body of Calliphora erythrocephala prior to metamorphosis

At the end of the larval feeding stage of Calliphora erythrocephala, ecdysteroids are most likely to be responsible for the rapid increase in acid phosphatase activity in the fat body. This is demonstrated by the precocious induction of the enzyme by 20-hydroxyecdysone in ligatured feeding-stage larvae weighing 55–70 mg. The hormone does not influence normal protein accumulation: this is inhibited by the ligature and is not restored by injection of the hormone.     

The induction of lysosomal enzyme activity in the fat body of Calliphora erythrocephala: Changes in the internal environment

The activity of the lysosomal marker enzyme acid phosphatase in the larval fat body of Calliphora erythrocephala increases during development, but not at the same rate throughout the tissue. During the feeding stage, the posterior region has a higher acid phosphatase activity than the anterior region. When the larvae cease feeding on the 5th day of development, the acid phosphatase activity of the inactive anterior lobe increases rapidly in a mosaic-cell pattern. When 4-day-old feeding stage larvae are starved, this increase occurs one day earlier than normally. After the emptying of the gut, the acid phosphatase activity of all the anterior cells both in normal and in starved larvae exceeds that of those in the posterior region.Transplantation experiments indicate that the induction of acid phosphatase activity in the fat body during normal development, especially in the anterior region, is caused by a change in the internal environment when the larvae cease feeding. Both RNA and protein synthesis are involved in this induction process. Inductive factors are present in 5-day-old larvae as well as during formation of the puparium. The competence of the feeding-stage fat cells to develop high acid phosphatase activity is acquired before the actual induction takes place.     

Gravity reception in the walking fly, Calliphora erythrocephala: Tonic and modulatory influences of leg afferents on the head position

The proprioceptive gravity receptor system of the fly, Calliphora erythrocephala, is functionally organized in a manner similar to the statocyst system in vertebrates, molluscs and crustaceans. It includes one system in which excitation is modulated by the gravitational stimulus, and another which exerts a tonic excitation on the neurones of the reflex arc between the leg receptors and the neck muscles. While the modulating system for the compensatory head movement of the walking flies is located only in the forelegs and the middle legs, the tonic excitation is mediated by receptors of all legs.     

Quantitative changes in free amino acids in Polytrichum formosum during development

The concentrations of each free amino acid in Polytrichum formosum have been determined for female gametangia at different developmental stages of     

Evidence for a sugar receptor (lectin) in the peritrophic membrane of the blowfly larva, Calliphora erythrocephala Mg. (Diptera)

For the first time a sugar receptor (lectin) has been localized by electron microscopy in an invertebrate. The peritrophic membrane of the blowfly larva, Calliphora erythrocephala, is shown here to express lectins with high specificity for mannose. The lectin is restricted to the lumen side of the peritrophic membrane. The surface of the midgut epithelium is devoid of mannose-specific lectins. It is suggested that the midgut epithelium has lost these lectins during the course of evolution in favour of the peritrophic membrane which is secreted by specialized cells only at the beginning of the midgut.Peritrophic membranes and the midgut epithelium lack lectins specific for galactose. The lumen side of the peritrophic membrane of the larvae has mannose and/or glucose residues, and it is densely packed with two species of bacteria, Proteus vulgaris and P. morganii. These also have mannose-specific lectins as well as mannose residues on their pili. The existence of mannose-specific receptors and mannose residues on both, peritrophic membranes and bacteria, leads to the assumption of mutual adherence between the two surfaces.     

Acidic amino acids in Reseda luteola

3-(3-Carboxyphenyl)alanine, (3-carboxyphenyl)glycine, 3-(3-carboxy-4-hydroxyphenyl)alanine and (3-carboxy-4-hydroxyphenyl)glycine occur in all parts of Reseda luteola. The concentrations of the two diastereoisomers of 2(S)-4-hydroxy-4-methylglutamic acid undergo seasonal variation, the highest concentrations occurring in the first part of the summer. Highest concentrations are found in the inflorescences. The two diastereoisomers of 2(S)-4-hydroxy-2-aminopimelic acid occur in appreciable amounts in all parts of the plant. They are easily transformed into two structurally different lactones, one of which is very unstable. The structures of these amino acids have been confirmed by synthesis. Green parts of R. luteola also contain substantial quantities of γ-glutamylglutamic acid and glutathione.     

Free amino acids in Crotalaria seeds

The free amino acids of seeds of 163 species of Crotalaria have been identified. Their pattern of distribution is compared with recent classifications of the genus and the possible ecological significance of their presence is discussed. Attention is drawn to the occurrence of toxic amino acids.     

The constancy and similarity of the amounts of free amino acids in inbred strains of Drosophila and outbred Calliphora

The composition of the free amino acids are compared in adults of two inbred strains of Drosophila subobscura and their hybrids, three inbred lines of Drosophila melanogaster, and in flies from a heterogeneous population of Calliphora erythrocephala. It appears that not only do the amounts of amino acid vary very little from fly to fly, but also very little between inbred lines. Furthermore, the relative amounts of the amino acids in Drosophila are similar to the relative amounts in the blowfly, Calliphora. This characteristic of invariant amounts of the free amino acids in these Diptera occurs in spite of the probably large numbers of genes affecting them.     

The role of free amino acids in osmoregulation of cricket blood (Acheta domesticus)

The blood volume increased during normal feeding, and did not decrease during fasting at the end of the stadium. The unexpectedly high blood volume of starved crickets might be an adaptation to increase chances for moulting via stretch receptor stimulation.The amount of blood amino acids was not changed by feeding, but increased with fasting or starvation. Thus amino acid levels in the blood were not directly related to amino acid input from the gut.The blood protein concentration did not change during starvation, but the amino acid concentration was 33% higher in starved crickets that drank water as opposed to those given saline to drink. Thus amino acid levels in the blood were not related directly to blood protein concentration.The blood amino acid concentration was 19–22 mM/l in response to salt intake by feeding crickets or starved crickets drinking saline. The concentration was 32–38 mM/l when the crickets were fasting prior to and after ecdysis or when starved with water to drink during the time when they would normally be feeding. The increase of amino acids during fasting was due to a proportional increase in all amino acids augmented by a 3 × increase in tyrosine. The increase during salt depleting starvation was due to a doubling of the two predominant amino acids proline and glycine. Proline and glycine were not increased in starved crickets drinking saline, thus starvation was not the reason for the increase. This is the first instance where specific amino acids have been implicated in osmoregulation.     

Free amino acids in the seeds of Acacia species

Free amino acids in the seeds of 80 species of Acacia have been determined. In addition to confirming the known difference in seed amino acid ‘patterns’ shown by species of the series Gummiferae on the one hand and species of the series Phyllodineae and Botryocephalae on the other, we have found that species of the series Vulgares Benth. show two additional ‘patterns’. One of these is common to some of the Afro-Asian species of the series which have been analysed and the other is common to species from America and Africa. One of the ‘marker’ amino acids of the Afro-Asian group is the neurotoxic lathyrogen α-amino-β-oxalylaminopropionic acid. The possible taxonomic and phylogenetic significance of these results is discussed, with special reference to five species A. albida, A. confusa, A. heterophylla, A. coulteri and A. kauaiensis.     

Muscle growth and protein synthesis in the puparia of Calliphora vomitoria

The effects of cycloheximide on the development of the dorsal longitudinal flight muscle of 3- to 5-day-old puparia of Calliphora vomitoria have been investigated. One μg of cycloheximide injected into the puparia reduced the incorporation of ¹⁴C phenylalanine and lysine into protein to 5 and 8 per cent of their normal levels. The cycloheximide was found to have produced its maximum effect within 2 hr of its injection and increasing the concentration did not further depress the amount of amino acid incorporation. The sixth dorsal longitudinal muscles continued to increase in length after the injection of cycloheximide and the elongation of the muscle fibres was accompanied by an increase in protein content in normal and cycloheximide-treated animals. An injection of colchicine (which is believed to disrupt microtubules) immediately halted muscle growth. Electron microscopy of the muscle fibre revealed that fibres from cycloheximide-treated animals contained myofilaments, although there were some differences in myofilament structure between normal and treated animals. The formation of the muscle fibres in the absence of protein synthesis is discussed.