Effect of gamma radiation on the metamorphic stages of Dermestes maculatus DeGeer (Coleoptera: Dermestidae)

The effects of gamma-radiation on all stages of the hide beetle Dermestes maculatus, DeGeer were studied. Eggs of D. maculatus were more susceptible to gamma radiation than other stages. Egg radiosensitivity decreased with increasing embryonic development. An absorbed dose of 200 Gy killed the 1st, 6th and 7th instar larvae, but the 4th and 5th instar larvae were more resistant. The developmental period increased in treated larvae. Pupae (24 h) treated with 150 Gy failed to eclose, but eclosion was not affected in older pupae. Adults from female pupae irradiated at 72 h with 150 Gy were infertile, but male pupae required more than 200 Gy for sterilization. The average number of eggs per female decreased with increasing doses when either the male or female of the pair was irradiated as puape or adults. Adult males were sterile after irradiation 300 Gy and adult females treated with the same dose failed to lay eggs. Newly emerged irradiated adults or female adults from irradiated 72-h-old pupae recovered some fertility after treatment with doses as high as 150 Gy. Adult males from irradiated 72-h-old pupae were treated at doses of 50 and 100 Gy showed a higher reproductive capacity at 60 days than at 15 days post-treatment. A dose between 200 and 300 Gy was necessary to provide complete sterility of 24-h-old adults.

Effect of ultraviolet- and X-irradiation on embryogenesis of the free-living nematode, Rhabditidae tokai: hatchability, morphogenesis and life span

Ultraviolet light (UV)- and X-irradiation reduced hatchability in a strain of free-living nematodes, Rhabditidae tokai. Sensitivities of eggs to UV and X-ray varied greatly depending on the lapse of time after oviposition. It was found that the eggs at 5 h after oviposition were most sensitive as compared with the eggs at other developmental stages. X-irradiation of the eggs resulted in significant life shortening of the worms after hatching, whereas UV-irradiation had no such life-shortening effect. Microscopic observations showed that the frequency of morphological anomalies in populations of unhatched embryos also varied depending on the stage at which UV- and X-irradiation was applied. These results suggest that X-irradiation but not UV-irradiation have a serious after-effect on worms hatched from treated eggs.

Biological effects of low-temporal, average-intensity, pulsed ultrasound

Studies with both plant and animal tissues show that, when the tissues contain micron-sized, stabilized gas bodies, pulsed ultrasound can produce damage at very low time-averaged intensities. However, it is the temporal peak intensity rather than the time-averaged intensity that is closely correlated with the effects observed. The data suggest that there may be thresholds for damage at peak intensities within an order of magnitude of 10 W/cm2.

The effect of pinealectomy, continuous light, and continuous darkness on metamorphosis of anadromous sea lampreys, Petromyzon marinus L

The role of the pineal complex in lamprey metamorphosis was investigated by examining the influence of pinealectomy and continuous light and darkness on the initiation of this event in anadromous sea lampreys, Petromyzon marinus L. Larval lampreys, which on the basis of a condition factor were considered likely to enter metamorphosis in July, were separated in May of 1979 and 1980 into the following groups: (1) intact controls, (2) sham-operated controls, (3) pinealectomized individuals, (4) those exposed to continuous light, and (5) those exposed to continuous light or dark. The importance of the pineal complex to metamorphosis was supported by morphological evidence that, in all presumably pinealectomized individuals that entered metamorphosis, the complex had apparently not been removed during the surgical procedure. The ways in which the pineal complex may be involved in lamprey metamorphosis are discussed.

The influence of X-rays on reproduction in Pseudeucoila bochei (Hymenoptera Cynipidae), a parasite of Drosophila melanogaster

The parasitic wasp Pseudeucoila bochei was the subject in experiments designed to detect a reliable method of mutation induction. Radiation doses of 360, 720, 1080, 1440, 1800 and 2160 R were given to pupae 15 or 18 days old or to freshly eclosed male and female wasps. The irradiation did not influence the survival of pupae. Dose-action responses were established and appeared to be dependent on the stage of development of the wasps at the moment of irradiation. The production of sons by virgin females showed that the germ cells of the adults were the most sensitive to irradiation. In contrast, the sperms of the male wasps irradiated as adults were the most resistant. Irradiation of males as pupae with 1880 or 2160 R on the 15th day or as adults led to a high frequency of amle progeny. The elimination of sperm cells from fertilization is discussed. Comparisons with Habrobracon, Nasonia and Drosophila showed that the germ cells of Pseudeucoila are more sensitive to irradiation. In the progeny from irradiated females and males 2 types of mutant were found, with yellow eye colour and with aberrations in the antennae.

Levels of liver glycogen during normal and radiation-induced metamorphosis in Rana cyanophlyctis

This study shows that significant changes in the pattern of glycogen deposition are brought about by irradiation with 2,000 R gamma-rays. The sharp fall during the 1st week can be attributed to its emergent mobilization. However, glycogen stored in the liver during the 2nd and 3rd week prior to the resorptive process substantiates the fact that tadpoles complete metamorphic transformations in spite of sublethal irradiation.

Responses of metamorphosing Taricha torosa to x rays

A single dose of 1000 rads of x rays administered to metamorphosing Taricha torosa larvae interferes selectively with some elements of the metamorphosing process without, apparently, affecting any major triggering mechanism. Though the predominant result is a failure to complete metamorphosis, metamorphosed irradiates showing larval pigmentation, vestigial gills, and non-protuberant eyes have been observed. Arrest of the normal thickening of the epidermis during metamorphosis and of the associated development of the epidermal melanophores is followed by regression of the pigment pattern to the larval form. This 1000-rad dose appears to kill half of a sample population in 30 days. A single dose of 200 rads, while allowing completion of metamorphosis, is fatal within some 3 months. The metamorphosed animals show predominantly adult characteristics.

Circadian control of larval growth rate in Sarcophaga argyrostoma

Larvae of the flesh fly, Sarcophaga argyrostoma, were reared in a range of environmental light cycles with periods from 21 to 72 hr, and containing either 12, 14, or 16 hr of white light. The mean length of larval development varied cyclically with the period of the driving light cycle. Protracted development occurred when the larvae were "driven" by light cycles containing a "short day" (12 hr of light) at periods close to their natural circadian frequency (about 24 hr) or multiples thereof. More rapid development occurred when the larvae were "driven" by 24-hr light cycles containing a "long day" (14 or 16 hr of light), or at periods far from their natural frequency (e.g., 36 or 60 hr).

Some effects of irradiation on the tick Rhipicephalus appendiculatus

Groups of Rhipicephalus appendiculatus ticks were given single doses of irradiation (range 0·25–16 krad) at different stages in their life-cycle: unfed nymphs, engorged nymphs, moulting nymphs and unfed adults. The effects of irradiation were assessed by evaluating the subsequent performances of the ticks when fed on rabbits. Observations were carried through until the viability of egg batches from surviving females had been recorded. Irradiation of unfed and engorged nymphs produced similar effects on the ticks, whilst irradiation of moulting nymphs and adults produced effects which were different from those produced on the other two groups but similar to each other. Ticks were in general unaffected at irradiation doses below 2 krad, but at this level and above, survival rates, mean engorged weights, percentage egg weights and viability of eggs were reduced, and feeding times were extended. Male ticks appeared to be more susceptible to the effects of irradiation than female ticks. Males irradiated at 4 krad were sterile, but since they survived doses considerably higher than this they might well prove suitably competitive in further trials should a sterile male release be considered feasable. The possibility is also considered of irradiating Theileria parva parasites in ticks and thus altering the parasites in some way that could be used in studies of immunisation of cattle against East Coast fever.

Response of newt larvae to x-irradiation

Graded doses of from 200 to 2000 rad of x-rays were administered to premetamorphic Taricha torosa larvae of various ages. General stunting, specific malformation, pigmentary damage, and a very shortened life-span occurred at all doses. There is an age-dependent dose response; some animals exposed to 200 and 600 rad survived to complete metamorphosis. Evidence is presented supporting a view that postmetamorphic epidermal melanocytes may be derived largely by division of an unpigmented progenitor cell type.