• Journal of Sericultural and Entomological Science
• /
• v.27 no.1
• /
• pp.24-30
• /
• 1985

The effect of some organic solvents on interrupting diapause of Bombyx mori eggs was examined to provide a clue to the mechanism of diapause initiation. Methyl alcohol and benzene proved to be efficient in developing the prospective diapause eggs upto the stage of hatching or body pigmentation of the embryos. On the other hand, most of the eggs soaked in chloroform and mixture solution of chloroform-methyl alcohol (2:1) died in the early embryonic developmental stage with yellow or red brown colours, and the egg weights decreased upto ca. 40% of the original weight 8 days after the treatments. Methyl alcohol treatment for 2, 5 and 10 min to the 5hr-old-eggs led to empergence of the larvae, with high incidence (70∼80%) in the race of Kumchu X Chonghwa and with low indidence (1∼4%) in Daezo. The effect of same treatment to 20hr old eggs decreased to ca. 10% in the emergence of larvae in Kumchn X Chonghwa and increased to 20∼30% in Daezo, while the effect disappeared shortly after the diapause initiation (48hr-old-eggs). Considering the high dependency upon the egg age of the sensitivity to solvents, it was supposed that initiation and termination of diapause may be controlled by different mechanism. It was also suspected that the solvents exert their effect on the permeability of the eggshell.

• Korean Journal of Environmental Biology
• /
• v.25 no.4
• /
• pp.370-377
• /
• 2007

The spawning host selection and adaptive characteristics in life history were investigated for Sarcocheilichthys nigripinnis morii which has similar habit of spawning with acheilognathine fishes. The fertilized eggs of the species were found in the mantle cavity of Corbicula papyracea and C. fluminea among the bivalves collected from same locality, meaning the species specific host selection for the spawning. We considered that the differences in the status of expanding egg membrane after hydration, fewer number of eggs settled into the mantle cavity and having eleutheroembryo with developed organ would be some evidences of specific reproductive strategy for this species. But the status of developed surface blood circulation was thought to be a compensation for the parasitism. The pigmentation of melanopore delayed to late embryo and the spot on the caudal region was a characteristics of this species appeared in the early life history.

• Korean Journal of Breeding Science
• /
• v.43 no.6
• /
• pp.532-537
• /
• 2011

'Seolgaeng' is a new Japonica rice variety developed from an 'Ilpumbyeo' mutant line, N-methyl-N-nitrosourea (MNU) treatment on fertilized egg cell, by a rice breeding team of National Crop Experiment Station, Rural Development Administration in 2001. This variety has about 134 days of growth duration from transplanting to harvesting in central plain area of Korea, a good semi-elect plant type and resistant to lodging with strong culm. The number of panicles/hill of 'Seolgaeng' is more than that of 'Hwaseongbyeo'. The milled rice appearance of this cultivar is an opaque, but it has amylose content (19.3%) similar to 'Hwaseongbyeo'. It is superior to hypae formation of Aspergillus orzyae in the making of fermented rice and amount of pigmentation in fermented rice by Monascus anka that of 'Ilpumbyeo'. This variety showed slow leaf senescence and considerable resistance to viviparous germination. It is moderately resistant to leaf blast and susceptible to bacterial blight, virus disease and insect pests. The yield performance of this rice cultivar is about 5.27 MT/ha in milled rice in local adaptability test for three years from 1999 to 2001). 'Seolgaeng' is adaptable to central and southern plain areas of Korea.

• Korean Journal of Clinical Laboratory Science
• /
• v.50 no.3
• /
• pp.284-288
• /
• 2018

The scuttle fly central nervous system (CNS) is unobservable during egg and larvae instar stage 1. During days 2~3 of larvae instar stage 2, the left and right hemisphere of the brain can be observed. Below the brain, the subesophageal ganglion (SOG) connects to the ventral nerve cord (VNC). During days 3~5 of larvae instar stage 3, the CNS enlarged slightly with no other changes. During days 1~3 of the pupal stage the CNS moved to the head with no distinguishable changes from the previous stage. During days 4~6 of the pupal stage, the left and right hemisphere of the brain had fused into one mass and the optic lobe (OL) located on the side of the brain completed its development. During days 7~9 of the pupal stage, the OL began to show eyeball pigment. The SOG was connected to the brain and the VNC began to separate, which was accompanied by an increase in nerve fibers. During days 10~12 of the pupal stage, the brain of the CNS and VNC was clearly distinguished and the brown pigmentation of OL became darker. During days 13~15 days of the pupal stage, the separated brain and VNC became connected by thin nerve fiber. The VNC began to separate into two with a greater increase in nerve fibers. The adult fly showed similar features to the previous stage, but the brain was located in the head and the VNC in the chest.

• Applied Microscopy
• /
• v.42 no.1
• /
• pp.17-26
• /
• 2012

Histologic and microstructural changes during the postembryonic development of the wolf spider Arctosa kwangreungensis were studied using light and scanning electron microscopy to examine the relationship between a morphological differentiation and behavioral properties. The postembryo with abdominal yolk sac was stayed inactive in the egg case because its muscular and visual systems were not fully developed to a functional level. The first instar spiderlings, developed from the postembryo by a first molting process, started to exhibit its pigmentation on their body cuticles. In particular, undifferentiated cell clusters of central nervous system (CNS) were densely distributed within the cephalothorax, and highly differentiated abdominal ganglion was observed. They had a characteristic visual system looks more like its adult counterpart, and had segmented appendages looks more like the tiny spiders containing well oriented muscular system. After 3rd instar, spiderlings grew more rapidly with accordance to their consistent growth and periodical molting processes. Thus, the relative area of CNS with respect to cephalothorax was gradually decreased, instead a pair of venom glands, musculature, and connectives occupied the residual area. It has been revealed that the early development of spider can be controled by the feeding condition of larval period, since histologic and microstructural differentiations in both appendages and optic system were completed at the second instar. In particular, behavioral properties of the wandering spiders that depend on vision and their running ability were deeply related to physiological differentiation of the microstructural development.