Biochemical changes in tissue composition of Periplaneta americana (Linn.) acclimated to high and low temperatures

1. 1.|Cold acclimation apparently favours an increase of water content in fat body, but not in coxal muscle, of cockroaches.

2. 2.|A remarkable enhancement in the accumulation of total protein in fat body characterizes the cold acclimation of cockroaches, particularly adult males (175% increase in protein/DNA ratio). The increase in protein content of coxal muscle during acclimination to 15°C, observed in nymphs (16%) and males (16%) but not in females, is less pronounced than that of fat body.

3. 3.|A diminution (28–32%) in the free amino acid/DNA ratio due to cold acclimation has been recorded in both coxal muscle and fat body of nymphs and females, but not in males.

4. 4.|No qualitative change occurs in the free amino acid spectrum of haemolymph and tissues of this insect during acclimation to 15 and 35°C.

5. 5.|An augmentation (15–30%) of the RNA/DNA ratio occurs in fat body and coxal muscle of nymphs and males but in fat body alone of females following cold acclimation.

6. 6.|The glycogen reserve has been shown to increase by up to 30% in fat body and coxal muscle of cold acclimated cockroaches compared to warm acclimated ones.

Dependence of the parasitoid Gonia cinerascens on the hormones of its lepidopterous hosts

Development of first instar larvae of Gonia cinerascens, which rest in the muscles of host caterpillars, is triggered by the release of the host's ecdysteroids when the juvenile hormone is absent. Ecdysteroids act on the parasitoid directly and at the same time induce physiological and biochemical changes in the host, which are indispensable for the parasitoid's development. These changes do not occur when metamorphosis of the host is suppressed with the juvenile hormone. Normally the parasitoids initiate development at the larval-pupal transformation of the host, but under experimental conditions, they do so whenever a high ecdysteroid titre is coupled with the proper internal environment in the host, that is in decapitated caterpillars, isolated host abdomens, and when implanted into host pupae. Activated parasitoids moult into the second instar and migrate to the exuvial space of the host; this migratory behaviour is also triggered by ecdysteroids and may be induced experimentally in the first instar parasitoids. Unknown clues direct the migrating parasitoids under the wings and appendages of the host pharate pupal stage. The second instar parasitoids, which anchor to the integument of the host pupae, apparently develop independently of the host's hormones: they can produce third instar larvae, pupae, and adult flies when cultured in vitro.     

Electron microscopical-immunocytochemical evidence of ecdysteroids in the prothoracic gland of Galleria mellonella

Summary Fixation of prothoracic glands of Galleria mellonella with a solution containing saponin permits immunocytochemical staining of the entire gland. By this means ecdysteroids were demonstrated electron microscopically to be present in the hyaloplasm and microtubules.Supported by Sächsische Akademie der Wissenschaften zu Leipzig     

Ultrastructure of the muscles of the dorsal diaphragm in Locusta migratoria

Summary The alary muscles of Locusta migratoria adults make up the major tissue of the dorsal diaphragm which separates pericardial and perivisceral sinuses in the abdomen. The alary muscles are striated with a sarcomere at rest measuring about 9 m. The Z-line has a staggered-beaded arrangement with A-bands and I-bands readily discernable. Thick myofilaments are surrounded by 10 or more thin filaments. The sarcoplasm has few mitochondria near the area of the Z-line, dyads are present and sarcoplasmic reticulum is poorly developed. Axons which innervate the alary muscle are either contained within invaginated folds of the sarcolemma of the muscle cells or the muscle cells send finger-like projections to envelop the axons. The synaptic terminals contain synaptic vesicles between 40 and 45 nm in diameter and a few electron-dense granules near or less than 170 nm in diameter. Away from synaptic terminals the axon profiles show few or no granules. The axons are accompanied everywhere by well-developed glial cells. This then is not typical neurosecretomotor innervation, however, the presence of electron-dense granules suggests the possibility of peptidergic neurotransmission.