Role of the chorion as a barrier to oxygen in the diapause of the silkworm,Bombyx mori L.

Okada, Mirei

doi:10.1007/bf02136945

Cited by 34 publications

(10 citation statements)

References 17 publications

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“…In addition, it was previously documented that the diapause process can be terminated by dechorionation (removal of the shell) (Okada, ; Takami, ). Horie et al .…”

Section: Introductionmentioning

confidence: 99%

“…() further showed that a physiological concentration of sorbitol (0.2 mol/L) inhibits the development of cultured dechorionated diapausing eggs, indicating that sorbitol plays a role in ensuring diapause, and that its concentration must be decreased for development to resume. It was supposed that a change in oxygen availability upon dechorionation is related to diapause termination in dechorionated eggs (Okada, ; Takami, ; Sonobe et al ., ). Yaginuma and Yamashita () demonstrated that a significant increase in O 2 uptake at 5°C coincides with diapause termination.…”

Section: Introductionmentioning

confidence: 99%

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Injury‐induced rapid activation of MAPK signaling in dechorionated eggs and larvae of the silkworm Bombyx mori

Chen

2016

Insect Science

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Previous study showed that diapause in Bombyx mori eggs can be terminated by dechorionation and that activation in the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) in dechorionated cultured eggs is involved in diapause termination. In the present study, the possible mechanism underlying activation of ERK upon dechorionation was further investigated. Results showed that mechanical injury of diapause eggs without medium incubation also resulted in rapid increase in the phospho-ERK levels and that injury increased the phospho-ERK levels at different stages of both diapause eggs and eggs in which diapause initiation was prevented by HCl. Effects of anaerobiosis on dechorionation-stimulated phospho-ERK levels showed that the mechanical injury itself but not the dramatic increase in oxygen uptake upon injury is involved in a rapid activation of ERK. Chemical anaerobiosis on dechorionation-stimulated phospho-ERK levels and the in vivo effect of anaerobiosis showed that the supply of oxygen also plays a role in ERK signaling. In addition, injury induced the phosphorylation of c-jun N-terminal kinases (JNKs) and p38 kinase, components of two parallel MAPK pathways. A kinase assay showed a dramatic increase in JNK kinase activity in egg lysates upon injury. When newly hatched first instar larvae were injured, an increase in the phospho-ERK levels similar to that in dechorionated eggs was observed. From the results, we hypothesize that the injury-induced rapid activation of MAPK signaling, which serves as a natural signal for embryonic development, is related to diapause termination in dechorionated eggs.

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“…In addition, it was previously documented that the diapause process can be terminated by dechorionation (removal of the shell) (Okada, ; Takami, ). Horie et al .…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Injury‐induced rapid activation of MAPK signaling in dechorionated eggs and larvae of the silkworm Bombyx mori

Chen

2016

Insect Science

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“…Accumulation of glycerol or other solutes under anoxia has also been observed in some insects (WILHELM and others 1961(WILHELM and others , S~M M E 1966(WILHELM and others , 1967. OKADA (1971) found that glycogen in the non-diapausing eggs is rapidly broken down under low oxygen partial pressure, just as observed in the diapausing eggs. Okada proposed that a common mechanism is operating in the polyol formation in the anaerobiosis and in the diapausing eggs.…”

mentioning

confidence: 61%

Carbohydrate Metabolism in the Eggs of the Silkworm, Bombyx Mori. Ii. Anaerobiosis and Polyol Formation

Kageyama

Ohnishi

1973

Dev Growth Differ

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In non-diapausing eggs incubated in nitrogen or in carbon monoxide, a part of glycogen was converted into sorbitol, glycerol, and lactate. When the treated eggs were recovered from the incubation in nitrogen before not more than 24 hr, glycogen was resynthesized from these polyols and lactate. This interconversion between glycogen and polyols or lactate is considered to be essentially the same phenomenon as that observed in the diapausing eggs. The results are discussed in relation to carbohydrate metabolism and energy supply in the eggs.

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“…But recent work by SATO and TAKE SUE(^^) has demonstrated the presence of a complete mitochondria1 electron-transport system including cytochrome c in eggs during diapause. OKADA (16) postulated that a structural change of chorion concomitantly occurs at the beginning of diapause, which prevents the penetration of oxygen into the embryos, and consequently the embryos become anaerobic. A recent report by SONOBE and his colleagues, however, has shown that no direct relationship exhibits between the chorion permeability to oxygen and the initiation of diapause (21).…”

Section: Discussionmentioning

confidence: 99%

Polyol Accumulation in in Vitro Systems of Bombyx Eggs

et al. 1980

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The mechanism of polyol accumulation in diapausing Bombyx eggs, conversion of [6-14C] glucose-6-phosphate into polyols and other neutral sugars was investigated in in vitro reaction systems. When crude homogenate or a press juice of the eggs was incubated with [6-14C]glucose-6-P, the labelled trehalose, sorbitol and glycezl accumulated in the reaction mixture. In the press juice incubation system of developing eggs at day I , 14C-sorbitol was detected in appreciable amounts, but it decreased rapidly with the development of the embryos. When the press juice was prepared from eggs in diapause, the formation of "C-sorbitol was 3-5 times grester in eggs at early stages (day 2 to day 4) than in developing eggs.In eggs of Bombyx mori, glycogen is converted into two polyols, sorbitol and glycerol, at the onset of and is resynthesized at the termination of the diapause (4, 5). The enzyme systems responsible for polyol accumulation in both diapause eggs and developing eggs have been studied, and some of them have been purified and characterized (5, 6 , 7, 8, 12, 13, 23, 24, 25). These studies reveal that the enzyme system responsible for the production of polyols from glycogen is present not only in diapause eggs but is also present in developing eggs, in the latter, however, polyol accumulation does not occur in natural conditions.In a series of experiments, CHINO (5) suggested that a block in electron transport systems occurs at the initiation of diapause and it causes the formation of reduced pyridine nucleotide coenzymes which, in turn, facilitate polyol formation. However, the nature of the regulatory mechanism in polyol accumulation still remains unclear. The purpose of the present study is to examine possible factors or conditions which cause polyol formation using in vitro reaction systems: the press juice system and the homogenate system. MATERIALS AND METHODS Silkworm eggsA bivoltine race, a hybrid of Nichi 106 and Daizo, was used. The procedures to obtain diapausing and devzloping eggs have been described previously (12). In some experiments, however, embryo development was initiated by treating diapause eggs with a 22 % HCI solution as reported by FUKUDA and KOHNO (10). ChemicalsGlucose-6-phosphate and yeast hexokinase (Type 111) were purchased from Sigma Chem. Co. Ltd.; [6-14C]glucose (specific activity, 2-4 mCi/mmole) from Daiichi Pure Chem.

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Role of the chorion as a barrier to oxygen in the diapause of the silkworm,Bombyx mori L.

Cited by 34 publications

References 17 publications

Injury‐induced rapid activation of MAPK signaling in dechorionated eggs and larvae of the silkworm Bombyx mori

Injury‐induced rapid activation of MAPK signaling in dechorionated eggs and larvae of the silkworm Bombyx mori

Carbohydrate Metabolism in the Eggs of the Silkworm, Bombyx Mori. Ii. Anaerobiosis and Polyol Formation

Polyol Accumulation in in Vitro Systems of Bombyx Eggs

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