• Biomedical Science Letters
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• v.28 no.4
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• pp.290-297
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• 2022

Through previous studies, the central nervous system (CNS) was collected by dividing the scuttle fly into larval, pupa, and adult stages by developmental stage, and the morphological characteristics were observed. In situ hybridization (ISH) using the collected central nervous system, it was possible to confirm the location and extent of expression of the neurotransmitter corazonin (Crz) at each stage of development. In this study, paraffin specimens were prepared using central nervous system tissues of 3rd instar larval stage of scuttle fly, which had completed in situ hybridization, and general histochemical staining (hematoxylin-eosin, H-E) and special histochemical staining (luxol fast blue-cresyl violet) was performed to observe the histological and cytological morphology characteristics of corazonin neurons. As a result, a variety of nerve cell body existed between many myelin sheath. The corazonin neurons compose cortex of central nervous system with other neurons congregating in this tissue and show larger cell body relatively in neurohistochemical analysis.

• Parasites, Hosts and Diseases
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• v.55 no.1
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• pp.47-54
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• 2017

The prevalence of cercarial infection in freshwater snails and their evolutionary trends were studied in Nakhon Nayok province, Thailand. A total of 2,869 individual snails were examined for parasitic infections. The results showed that 12 snail species were found to host larval stages of trematodes with an overall prevalence of 4.7%. The infected specimens included 7 types at the cercarial stage; cercariae, megalurous cercariae, echinostome cercariae, furcocercous cercariae, parapleurolophocercous cercariae, virgulate cercariae, and xiphidiocercariae. Regarding molecular identification, ITS2 sequence data of each larval trematode were analyzed, and a dendrogram was constructed using the neighbor-joining method with 10,000 replicates. The dendrogram was separated into 6 clades (order/family), including Echinostomatida/Echinostomatidae, Echinostomatida/Philophthalmidae, Opisthorchiida/Heterophyidae, Plagiorchiida/Prosthogonimidae, Plagiorchiida/Lecithodendriidae, and Strigeatida/Cyathocotylidae. These findings were used to confirm morphological characteristics and evolutionary trends of each type of cercariae discovered in Nakhon Nayok province. Furthermore, this investigation confirmed that the ITS2 data of cercariae could be used to study on phylogenetic relationships or to determine classification of this species at order and/or family level when possible.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.6
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• pp.457-467
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• 1990

Sessile barnacle, Balanus trigonus Darwin, was collected from the intertidal rocks and the external shells of bivalve Mylius coruscus. The nauplius and cyprid larvae were cultured in a constant temperature cabinet at a temperature of $20^{\circ}C$ and a light regime of 14 h light and 10 h darkness. Larval development includes the six nauplius stages and a cyprid stage prior to settlement and metamorphosis to the young adult. Morphological characteristics including antennules, antennae and mandibles are described and illustrated. All nauplius larvae have trilobed labra typical in balanoides. The developmental time taken from newly hatched nauplius I to cyprid was $9\~13$ days and averaged 11 days.

• Applied Microscopy
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• v.43 no.1
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• pp.21-26
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• 2013

The oriental fruit moth (Grapholita molesta Busck) and the peach fruit moth (Carposina sasakii Matsumura) are the most severe insect pests affecting apple orchards in Korea. To prevent an outbreak of these two species and to control these agricultural insect pests, it is important to identify them accurately. However, it is hard to classify them when they were in the larval stage since they tunnel into the apple fruit. In this study, surface structures of the two species of larvae were observed using stereo microscope and scanning electron microscope. Distinct differences between the two species of larvae were found. The prothorax spiracles of oriental fruit moth larvae were approximately twice as large as those of peach fruit moth larvae. The arrangements of subventral setae, located around the proleg, were different between oriental fruit moth and peach fruit moth larvae. Furthermore, subdorsal setae of oriental fruit moth were located next to the spiracle on the 8th abdominal segment, while that of peach fruit moth was located above the spiracle. The identification of the two species of larvae observed in this study was confirmed using polymerase chain reaction-restriction fragment length polymorphism method. Surface structural differences are intrinsic characteristics for each species of larvae and can easily be identified using stereo microscope. These specificities will be helpful where a large number of field-collected larvae need to be identified routinely in pest control research.

• Parasites, Hosts and Diseases
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• v.34 no.3
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• pp.161-168
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• 1996

We observed the morphological characteristics and identified the species of gnathostome larvae obtained from the imported Chinese loaches. The early third-stage larvae ($EL_3$) were collected from viscera of the loaches and a part of them were infected to mice. The advanced third-stage larvae ($AdL_3$) were recovered from the mice at 4 weeks post-infection. both larval worms were fixed loth 10% formalin, cleared in alcohol-glycerin solution, mounted with glycerin-jelly, and observed. A total of 369 $EL_3$ were collected from viscera of 9,493 Chinese loaches. The whole body of $EL_3$ was covered with about 190 transverse rows of minute cuticular spines and $0.624{\;}{\times}{\;}0.101{\;}mm$ in average size. A pair of lips were protruded at the anterior end, and the muscular esophagus and brownish intestine were followed. The characteristic head bulb was provided with 4 rows of hooklets. The average number of hooklets in the respective row was 36.7, 39.5, 41.6 and 44.3 posteriorly $AdL_3$ was $2.660{\;}{\times}{\;}0.346{\;}mm$ in average size, and retained the esophagus (about 0.755 mm length) and cervical sac (about 0.355 mm length). The average number of hooklets in the respective row on the head bulb was 39.0, 41.9, 43.9 and 45.6, posteriorly. On the basis of the morphological characteristics, they were identified as the third-stage larvae of Gnathostomc hispinun.

• Korean Journal of Ichthyology
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• v.13 no.1
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• pp.74-84
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• 2001

The early developmental stages, growth and morphological changes of the Korean bullhead, Pseudobagrus fulvidraco, were studied from a series of reared specimens. Details of the early developmental stages are illustrated with special reference to morphological transformations. Egg and sperm of Korean bullhead were obtained from mature adults under hormonal treatment, fertilized artificially, and incubated in the aquarium. The incubation period of fertilized eggs was 55 to 66 hours at a temperature of 24.9${\pm}$0.34$^{\circ}$. Larvae were fed successively with Artemia salina and Daphnia magna for 2 to 15 days and artificial food after 20 days. Fertilized eggs were adhesive and spherical with a diameter of 2.04mm(n = 100). The mean total length of newly hatched larvae was about 4.92${\pm}$0.33 mm. Mouth opening occurred on one-day-old yolk-sac larvae, and initial feeding was observed on the third day after hatching. The morphological transitions from larvae to juvenile and juvenile to young stages occurred when the fish reached about 17 mm in total length (about 13days after hatching) and about 32 mm in total length (about 30 days after hatching), respectively. Many changes in proportion of body parts to total length were observed at about 7~8 mm and 30~32 mm, corresponding to the transformations from larvae to juvenile and from juvenile to young, respectively. In comparing relative growth of each body part against total length, those characteristics related to head parts showed positive growth in the pre-larval stages, while those concerning mobile abilities showed positive growth in the post-larval stage.

• Parasites, Hosts and Diseases
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• v.45 no.3
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• pp.191-198
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• 2007

A total of 205 larval gnathostomes were collected from 18 (22.5%) of 80 red banded odd-tooth snakes, Dinodon rufozonatum rufozonatum, which had been smuggled from China and confiscated at Customs in Susan, Republic of Korea. In order to identify the species, some of the larvae were observed by a light microscope and a scanning electron microscope (SEM). The larvae were $2.18{\times}0.29mm$ in average size, and had a pair of lips at the anterior end, a muscular esophagus, 2 pairs of cervical sacs, and brownish intestines. The head bulb was characteristically equipped with 4 rows of hooklets; the average number of hooklets in each respective row was 38.6, 40.5, 41.5, and 43.7. In SEM views, the mouth evidenced a pair of lateral lips of equal size in a half-moon shape. Each lip featured a couple of labial papillae and a small amphid located between the 2 papillae. The hooklets on the head bulb had single-pointed, posteriorly-curved tips. The cuticular spines were larger and more densely distributed on the anterior part of the body, and decreased gradually in size and number toward the posterior body. On the basis of these morphological characteristics, the larvae were identified as the third stage larvae of Gnathostoma hispidum.

• Korean journal of applied entomology
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• v.42 no.1
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• pp.1-7
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• 2003

Morphological characteristics, developmental period, and seasonal occurrence of Adeia leucomelas (L.) were investigated from 1999 to 2000. In addition, consumption of sweetpotato as food was also examined. Adults of A. leucomelas were dark-brown and body lengths of females and males were 20.2 mm and 18.9 mm, respectively, Wing expanse of female and male was 33.7 mm and 29.4mm, respectively. Egg was flat round-shape. Larva was light yellow-green to dark-brown with 3.3-53.5 mm. Pupa was deep-brown and 15.1 mm in length. Developmental periods of A. leucomelas from egg to adult emergence at different temperatures of 15, 20, 25, and 30$^{\circ}$C were 108.5, 70.7, 40.2, and 29.1 days, respectively, Developmental threshold (DT) and effective accumulative temperatures were estimated as 10.7$^{\circ}$C and 67.5 DD in egg stage, 11.0$^{\circ}$C and 275.1 DD in larval stage and 9.3$^{\circ}$C and 244.6 DD in pupal stage, respectively. The longevity of adult female was shortened with increment of temperature, whereas the total numbers of eggs laid by a female were increased. The larvae of A.leucomelas occurred from mid-June to early October, and population reached its peak during early to mid-September in Jeonbuk province. Food consumption of A. leucomelas was highest at 20-25$^{\circ}$C. Food consumption of 1 st, 2nd, 3rd, 4th, and 5th larvae of A. leucomelas per day at 25$^{\circ}$C was 0.4, 3.6, 19.6, 40.7, and 78.9 $\textrm{cm}^2$, respectively.

• Parasites, Hosts and Diseases
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• v.60 no.5
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• pp.345-352
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• 2022

Chitinase AO-801 is a hydrolase secreted by Arthrobotrys oligospora during nematode feeding, while its role remained elusive. This study analyzed the molecular characteristics of recombinant chitinase of Arthrobotrys oligospora (reAO-801). AO-801 belongs to the typical glycoside hydrolase 18 family with conserved chitinase sequence and tertiary structure of (α/β)₈ triose-phosphate isomerase (TIM) barrel. The molecular weight of reAO-801 was 42 kDa. reAO-801 effectively degraded colloidal and powdered chitin, egg lysate, and stage I larval lysate of Caenorhabditis elegans. The activity of reAO-801 reached its peak at 40℃ and pH values between 4-7. Enzyme activity was inhibited by Zn2⁺, Ca2⁺, and Fe3⁺, whereas Mg2⁺ and K⁺ potentiated its activity. In addition, urea, sodium dodecyl sulfate, and 2-mercaptoethanol significantly inhibited enzyme activity. reAO-801 showed complete nematicidal activity against C. elegans stage I larvae. reAO-801 broke down the C. elegans egg shells, causing them to die or die prematurely by hatching the eggs. It also invoked degradation of Haemonchus contortus eggs, resulting in apparent changes in the morphological structure. This study demonstrated the cytotoxic effect of reAO-801, which laid the foundation for further dissecting the mechanism of nematode infestation by A. oligospora.

• The Korean Journal of Malacology
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• v.30 no.4
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• pp.303-309
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• 2014

The development of Japanese geoduck, Panopea japonica, grown under culture conditions, has been examined through the morphological characteristics in fertilized egg, larvae and juvenile. Gametes were stripped from ripe broodstock and placed into two separate containers. Eggs were washed through a $40{\mu}m$ sieve and fertilized with dilute sperm solution. Developing larvae were maintained at $19{\pm}1^{\circ}C$. Fertilized eggs with $81.6{\mu}m$ diameter developed to trochophores within 14 h and to D-stage larvae ($116{\mu}m$ shell length) within 27 h. Larvae were spontaneously settled at shell length of $311{\mu}m$ after 20 days. The hatching from fertilized eggs and larval rearing were normally available in $18.5-21.5^{\circ}C$, and the growth was good in a cashmilon substrate, as well as sand. After rearing of day 108 from metamorphosis, the shell length of juvenile P. japonica reached 13 mm, and growth rate of shell length of the juvenile was $117.5{\mu}m/d$.