Termination Of Diapause In Eggs Research Articles

Geographical variation in egg diapause inSympetrum frequens

The effects of photoperiod and temperature on the termination of egg diapause were examined in Sympetrum frequens. Eggs were obtained from adult females collected from three locations in Japan and incubated under short- or long-day photoperiods at a constant temperature of 25, 20, or 15°C. Egg diapause was eventually terminated in all treatments. Because differences in the average developmental time were small among the temperature treatments, it was concluded that the rate of diapause development is more rapid at lower temperatures, as in other Odonata species. A clear geographic trend was not found in the egg period, which may reflect the life cycle of S. frequens: the timing of reproduction is the same or even earlier in higher than in lower latitudes. Relatively large variations in embryonic period were found among populations and even within a population at 15°C, suggesting that the rate of diapause development is also variable. The results also suggested that a short photoperiod might prevent S. fre...

Effects of juvenile hormone analogs and 20-hydroxyecdysone on diapause termination in eggs of Locusta migratoria and Oxya yezoensis

To understand the hormonal control of embryonic diapause, juvenile hormone analogs (JHAs), methoprene and hydroprene, and 20-hydroxyecdysone (20E) were applied onto diapause eggs of Locusta migratoria and Oxya yezoensis. These insects enter diapause at the mid-stage of embryogenesis prior to blastokinesis. Topical application of JHAs significantly facilitated diapause termination in both species but JHA-treated embryos underwent abnormal morphogenesis, pigmentation and sclerotization without dorsal closure. The Locusta eggs immersed in the 20E solution for 24 h terminated diapause in a dose-dependent manner. We also investigated phosphorylation of extracellular signal-regulated kinase (ERK), a member of mitogen-activated protein kinase (MAPK), during diapause-terminating process of Locusta migratoria and found that ERK was activated either by cold exposure or JHA treatment. The possible involvement of the hormones and ERK in embryonic diapause and the possibility of ecdysteroids synthesis by prothoracic glands of diapause embryo were proposed.

Effect of anoxia on diapause termination in eggs of the false melon beetle, Atrachya menetriesi

The effect of anoxia on diapause development in the leaf beetle Atrachya menetriesi was investigated to elucidate the role of oxygen in regulation of egg diapause. While anoxia alone had no effect on diapause termination, it decreased diapause intensity before chilling. Such an effect reached a maximum level when anoxia lasted for about 10 days. Anoxia applied during the pre-diapause stage also reduced diapause intensity. On the other hand, anoxia terminated diapause when the diapause intensity had been lowered by sufficient duration of chilling (50 days at 7.5 °C). The effect of anoxia was temperature dependent; the larger effect was elicited when anoxia was combined with a higher temperature. A 50-day chilling caused more than 20% of eggs to terminate diapause upon transfer to warm conditions. However, when this chilling period was interrupted on the 20th day by a 5-day exposure to a high temperature of 20, 25 or 30 °C, the effect of the former chilling was cancelled partially or completely, suggesting that warming reversed diapause development. This reversing effect of a high temperature, however, was not manifested when the warming was combined with anoxia. The results suggest that anoxia inhibits diapause reversal and facilitates a certain process of diapause development. The sequence of exposure to anoxia and chilling is not important.

Oxygen consumption in relation to sorbitol utilization at the termination of diapause in eggs of the silkworm, Bombyx mori

Rates of oxygen consumption were followed throughout the entire period of diapause in eggs of Bombyx mori. In non-diapause eggs at 25°C, O 2 uptake was divisible into three phases, corresponding to morphogenetic processes. In diapause eggs at 25°C, O 2 uptake showed a peak (100 μl/g eggs/h) at 1 day and then suddenly dropped to reach a level of 8–10 μl/g eggs/h at 10 days and thereafter. To break diapause, eggs were exposed to 5°C for varying periods. When O 2 uptake was measured at 5°C, it remained at 6 μl/g eggs/h. When eggs were chilled for increasing periods and O 2 uptake was measured immediately after warming to 25°C, the rates increased after a lag phase. In HCl-treated eggs, O 2 uptake increased immediately after acid-treatment. In all cases, highly increasing O 2 uptake at 25°C coincided with termination of diapause. These results were discussed in relation to sorbitol utilization at the termination of diapause.

Does an enzyme activity capable of phosphorylating sorbitol control utilization of sorbitol at the termination of diapause in eggs of the silkworm, Bombyx mori?

1. 1. An enzyme activity capable of phosphorylating sorbitol was examined in the crude extracts from eggs of the silkworm, Bombyx mori. 2. 2. The optimum pH was approximately 9.5. The apparent K m values for ATP and sorbitol were about 0.12 and 2.3 mM, respectively. The full activity demanded 3 mM of Mg 2+. 3. 3. The activity remained at low and almost constant levels during the entire period of diapause. However, during post-diapause development, the activity increased from the stage of larval differentiation to the time of larval hatching. 4. 4. The above results suggested that the enzyme activity to phosphorylate sorbitol did not control the utilization of sorbitol at the termination of diapause. Further, its activity was discussed in relation to the maintenance of physiological levels of sorbitol-6-phosphate in hemolymph of larvae.

Termination of egg diapause by imidazoles in the silkmoth, Antheraea yamamai.

Termination of egg diapause by imidazoles in the silkmoth, Antheraea yamamai.

Diapause termination in eggs of the stonefly Arcynopteryx compacta (McLachland) in relation to dehydration and cold hardiness

In the alpine regions of Southern Norway, eggs of the stonefly Arcynopteryx compacta are oviposited in small streams and lake outlets. During ice enclosure, eggs avoid freezing by supercooling and lose about two-thirds of their water content by shrinkage due to osmotic outflux of body water. The eggs enter diapause in autumn at an early stage of embryogenesis. The termination of diapause in 50–55% of eggs kept at 3°C for 3 or 6 months, arises from the effect of chilling on diapause development. The dehydration, however, serves as a diapause-terminating cue. For water contents down to 41%, the termination of diapause seems directly correlated with the degree of dehydration. Treatments with juvenile hormone were also effective in terminating diapause. The termination may therefore be linked to a temporary elevation in juvenile hormone titre by dehydration. Fully hydrated eggs supercool to about −26.5°C, and withstand ice enclosure for 3 days at −22°C. The elevation of supercooling point, water content and depletion of thermal hysteresis-producing proteins correspond with the initiation of postdiapause development. Also ice-enclosure for 3 days at −15 and −18°C proved fatal at this embryonic stage. The loss of cold hardiness could not be related to termination of diapause per se. Eggs remained cold hardy at 3°C as long as the postdiapause development was prevented during the thermally controlled quiescence. The physiological and biochemical mechanisms which underlie adaptation to cold, however, are specific for an early stage of embryogenesis.

Freeze tolerance in animals

Freeze tolerance in animals

Malate-aspartate cycle as an effective hydrogen shuttle at the termination of diapause in the eggs of Bombyx mori

The enzymes, which constitute the malate-aspatate cycle as a hydrogen shuttle, were examined in the eggs of Bombyx mori. Glutamate-oxaloacetate transaminase (GOT) and malate dehydrogenase (MDH) were found in both cytosolic and mitochondrial compartments of the eggs of silkworms and had specific kinetic properties. The activities of these enzymes were correlated with embryonic development and attained maximum levels at larval hatching. The activities of mitochondrial GOT and MDH increased in diapause eggs which were chilled at 5°C for more than 20 days. A further and rapid increase in the activities of mitochondrial GOT and MDH was induced by HCl-treatment of the chilled eggs. However, activities of the mitochondrial enzymes in non-diapause eggs were not influenced by chilling. The reconstruction experiments with intact mitochondria showed the occurrence of the malate-aspartate cycle in the silkworm eggs. The functional significance of the malate-aspartate cycle as a hydrogen shuttle is discussed in relation to NAD-sorbitol dehydrogenase at the termination of diapause in silkworm eggs.

Temperature dependent sorbitol utilization in diapause eggs of the silkworm,Bombyx mori

A series of experiments was conducted to determine whether the interconversion of glycogen and sorbitol at the initiation and termination of diapause in eggs of the silkworm,Bombyx mori was influenced by low temperatures (5°C and 1°C). The conversion of glycogen to sorbitol and glycerol at the initiation of diapause was not affected by exposure to 5°C and 1°C. Chilling diapause eggs at 5°C for over 70 days resulted in a progressive conversion of sorbitol to glycogen. Transfer to 1°C after chilling to 5°C led to a decrease in sorbitol and glycerol conversion. While continuous chilling at 1°C completely inhibited sorbitol utilization for at least 400 days, sorbitol began to decrease immediately following transfer to 5°C. In contrast, glycerol utilization was not prevented by acclimation to 1°C, but a delayed decrease occurred. Continuous exposure to 1°C delayed hatching for a period of 440 days, whereas acclimation to 5°C resulted in 100 per cent hatching by about 100 days. A low, or high acclimation temperature 1°C or 5°C produce different effects on sorbitol utilization and termination of diapause in silkworm eggs.

Observations on the termination of diapause in eggs of the wheat bnlb fly (Delia coarctata (Fall.)) and soil temperature

SUMMARYThe temperature of the soil 15 cm deep was recorded before, during and after hatching of wheat bulb fly eggs at several sites in eastern Scotland during 1976 and 1978–80 inclusive. Eggs were extracted from soil cores and examined microscopically to monitor the progress of hatching. In 1976, 1978 and 1979, the difference between the minimum and maximum soil temperatures was small just before the start of hatching and large at or immediately afterwards. The termination of diapause and initiation of hatching of wheat bulb fly eggs in Scotland appeared to be associated with diurnal fluctuations of more than 5°C between the minimum and maximum soil temperatures.

NAD-dependent sorbitol dehydrogenase activity in relation to the termination of diapause in eggs of Bombyx mori

Some properties of NAD-dependent sorbitol dehydrogenase (NAD-SDH) were determined in crude extracts from chilled, diapause eggs of Bombyx mori. Optimum pH was approx. 8.8 and the apparent K m values for NAD and sorbitol were 0.20 mM and 136 mM, respectively. In the reaction, sorbitol was stoichiometrically converted to fructose, but glycerol and mannitol were not oxidized. During early embryonic development (up to 2 days after oviposition) NAD-SDH activity was almost undetectable in both non-diapause and diapause types of eggs. The activity remained at this level in the diapausing eggs while it increased with age in the non-diapausing ones. After chilling the diapause eggs for 3 months, NAD-SDH activity began to increase gradually and then rose markedly. Also, a rapid increase in NAD-SDH activity was observed in eggs which were treated with HCl to break diapause quickly. These results together with the changing patterns in sorbitol concentrations in the eggs suggest that NAD-SDH is a key enzyme for sorbitol degradation at the termination of diapause in eggs of B. mori. The biochemical significance of NAD-SDH is also discussed in relation to the pathway of glycogen synthesis from sorbitol.

The Effect of Ammonia on the Rate of Termination of Diapause in Eggs of Acheta Commodus (Walk.) (Orthoptera : Gryllidae)

Certain ammonium compounds applied at a concentration of o� 04M proved highly effective in terminating diapause in eggs of Acheta. The only obvious characteristic in common between the effective compounds was that all of them had an organic anion, whereas those with an inorganic acid radical were ineffective.

Termination of Diapause in Acheta by Urea

THE rate of termination of diapause in eggs of Acheta commodus (Walk) has a negative temperature coefficient within the range −16.5 to +5° C.1. It has been reported by Jacobsen and Christensen2 that the initial stages of denaturation of β-lactoglobulin by urea has a negative temperature coefficient. Accordingly, experiments have been carried out with certain denaturants, primarily urea, for evidence of any effect on diapause. The attempt was made to incorporate the chemicals into the eggs by making use of the capacity of Orthopteran eggs to take up water during their development. In Acheta the uptake of water occurs slightly later than the onset of diapause3.

The Effects of Sub-Zero Temperatures on The Embryonic Diapause of Acheta Commodus (Walk.) (Orthoptera)

The effects of temperature on the termination of diapause in eggs of Acheta commodu8 were investigated over the range of -16� 5 to + 12� SoC; the effects on the entry into diapause were also measured by exposing pre-diapause eggs to temperatures of -10�0 to +12�SoC.

Physiological Characteristics of the Diapause Grasshopper Egg. I. The Stability of the Diapause Condition

Previous articleNext article No AccessPhysiological Characteristics of the Diapause Grasshopper Egg. I. The Stability of the Diapause ConditionJoseph Hall Bodine and Wilbur A. RobbieJoseph Hall Bodine Search for more articles by this author and Wilbur A. Robbie Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 13, Number 4Oct., 1940 Article DOIhttps://doi.org/10.1086/physzool.13.4.30151587 Views: 2Total views on this site Citations: 4Citations are reported from Crossref Journal History This article was published in Physiological Zoology (1928-1998), which is continued by Physiological and Biochemical Zoology (1999-present). PDF download Crossref reports the following articles citing this article:Kurako Kidokoro, Yoshikazu Ando Effect of anoxia on diapause termination in eggs of the false melon beetle, Atrachya menetriesi, Journal of Insect Physiology 52, no.11 (Jan 2006): 87–93.https://doi.org/10.1016/j.jinsphys.2005.09.006V. B. Wigglesworth Development in the Egg, (Jan 1972): 1–26.https://doi.org/10.1007/978-94-009-5973-6_1Eleanor H. Slifer The effects of xylol and other solvents on diapause in the grasshopper egg; together with a possible explanation for the action of these agents, Journal of Experimental Zoology 102, no.33 (Aug 1946): 333–356.https://doi.org/10.1002/jez.1401020307 Joseph Hall Bodine , and Wilbur A. Robbie Physiological Characteristics of the Diapause Grasshopper Egg: II. Changes in Density and Weight during Development, Physiological Zoology 16, no.33 (Sep 2015): 279–287.https://doi.org/10.1086/physzool.16.3.30151700