Magnetic characterization of Daphnia resting eggs

This study characterized the magnetic materials found within Daphnia resting eggs by measuring static magnetization with a superconducting quantum interference device (SQUID) magnetometer, after forming two types of conditions, each of which consists of zero-field cooling (ZFC) and field cooling (FC). Magnetic ions, such as Fe(3+), contained in Daphnia resting eggs existed as (1) paramagnetic and superparamagnetic particles, demonstrated by a magnetization and temperature dependence of the magnetic moments under an applied magnetic field after ZFC and FC, and (2) ferromagnetic particles with definite magnetic moments, the content of which was estimated to be very low, demonstrated by the Moskowitz test. Conventionally, biomagnets have been directly detected by transmission electron microscopes (TEM). As demonstrated in this study, it is possible to nondestructively detect small biomagnets by magnetization measurement, especially after two types of ZFC and FC. This nondestructive method can be applied in detecting biomagnets in complex biological organisms.     

Relationship Between Egg Viability and Population Densities of Meloidogyne incognita on Cotton

Cotton seedlings were inoculated with a range of initial populations (Pi) of Meloidogyne incognita in greenhouse experiments to test the relationship between nematode population densities and egg viability. In two of three experiments, a significant (P < 0.05) negative linear relationship was detected between percentage of hatch of first generation eggs and log Pi. A similar relationship between hatch and root-gall index was observed. In two experiments numbers of eggs judged to be nonviable based on appearance were significantly greater (P < 0.05) in the highest Pi (60,000 eggs/seedling) treatments than in treatments with lower Pi (600-6,000 eggs/seedling). It was concluded that Pi affects egg viability measured as percentage of hatch and that this relationship may play a role in the density-dependent winter survival rates of Meloidogyne species.     

Discovery of taeniid eggs from a 17th century tomb in Korea

Even though Taenia spp. eggs are occasionally discovered from archeological remains around the world, these eggs have never been discovered in ancient samples from Korea. When we attempted to re-examine the archeological samples maintained in our collection, the eggs of Taenia spp., 5 in total number, were recovered from a tomb of Gongju-si. The eggs had radially striated embryophore, and 37.5-40.0 μm×37.5 μm in size. This is the first report on taeniid eggs from ancient samples of Korea, and it is suggested that intensive examination of voluminous archeological samples should be needed for identification of Taenia spp.     

Effects of Disinfectants on Larval Development of Ascaris suum Eggs

The objective of this study was to evaluate the effects of several different commercial disinfectants on the embryogenic development of Ascaris suum eggs. A 1-ml aliquot of each disinfectant was mixed with approximately 40,000 decorticated or intact A. suum eggs in sterile tubes. After each treatment time (at 0.5, 1, 5, 10, 30, and 60 min), disinfectants were washed away, and egg suspensions were incubated at 25˚C in distilled water for development of larvae inside. At 3 weeks of incubation after exposure, ethanol, methanol, and chlorohexidin treatments did not affect the larval development of A. suum eggs, regardless of their concentration and treatment time. Among disinfectants tested in this study, 3% cresol, 0.2% sodium hypochlorite and 0.02% sodium hypochlorite delayed but not inactivated the embryonation of decorticated eggs at 3 weeks of incubation, because at 6 weeks of incubation, undeveloped eggs completed embryonation regardless of exposure time, except for 10% povidone iodine. When the albumin layer of A. suum eggs remained intact, however, even the 10% povidone iodine solution took at least 5 min to reasonably inactivate most eggs, but never completely kill them with even 60 min of exposure. This study demonstrated that the treatment of A. suum eggs with many commercially available disinfectants does not affect the embryonation. Although some disinfectants may delay or stop the embryonation of A. suum eggs, they can hardly kill them completely.     

Infection status of Clonorchis sinensis in residents of Hamyang-gun,Gyeongsangnam-do,Korea

Oriental liver fluke (Clonorchis sinensis) infection was surveyed among residents of Hamyang-gun, Gyeongsangnam-do, Korea during the period of January 2001 to March 2002. Total 1,041 stool samples were collected from residents who visited Public Health Center and its branches in Hamyang-gun and examined using formalin-ether sedimentation method. The overall egg positive rate was 16%, male showing higher positive rate (21%) than female (10%). The age group of 30 to 50 years had the highest egg positive rate of C. sinensis from 20% to 22%. The positive examinees were treated with praziquantel and educated individually to prevent reinfection. Egg positive rate in this area was decreased when compared with results recorded in the past, however, still remained more than 10%. This study suggests that periodic examination, treatment as well as education of residents should be continued and systematized.     

A case of chronic cerebral paragonimiasis westermani

We report a chronic cerebral paragonimiasis from a 41-year-old Korean man who complains a headache and weakness of left motor neuron components. Magnetic resonance images of the brain revealed conglomerates of multiple ring-like enhancements in temporo-occipital and frontal lobes of the right hemisphere. An intradermal test for paragonimiasis westermani was positive. The patient was born near an endemic area of paragonimiasis and used to eat boiled or grilled freshwater crayfish in his childhood. Nodules in the brain were resected through craniotomies. The eggs of P. westermani were identified pathologically and parasitologically in the calcified necrotic lesions. Examinations on sputum and fecal specimens for the eggs of P. westermani were shown to be negative and a chest radiograph was normal. It is presumed that the brain lesions were formed by P. westermani approximately 30 years ago.     

Comparison of HMOX1 expression and enzyme activity in blue-shelled chickens and brown-shelled chickens

Blue egg coloring is attributed to biliverdin derived from the oxidative degradation of heme through catalysis by heme oxygenase (HO). The pigment is secreted into the eggshell by the shell gland. There is uncertainty as to whether the pigment is synthesized in the shell gland or in other tissues. To investigate the site of pigment biosynthesis, the expression of heme oxygenase (decycling) 1 (HMOX1), a gene encoding HO, and HO activity in liver and spleen were compared between blue-shelled chickens (n = 12) and brown-shelled chickens (n = 12). There were no significant differences in HMOX1 expression and HO activity in these tissues between the two groups. Since the liver and spleen, two important sites outside the shell gland where heme is degraded into biliverdin, CO and Fe²⁺, did not differ in HO expression and activity we conclude that the pigment is most likely synthesized in the shell gland.     

Enterobius vermicularis egg positive rate of pre-school children in Chunchon, Korea (1999)

Pre-school children were examined for the presence of Enterobius vermicularis egg by perianal swab method. We visited 67 nurseries and 25 kindergartens between January, 1999 and April, 1999 in Chunchon, Korea. Of the 4,711 children examined, 434 (9.2%) were found to be positive for E. vermicularis egg. The egg positive rates of boys and girls were 10.1% and 8.1%, respectively. The rates were 7.8% in kindergartens and 9.7% in nurseries. Positive rate of 50 institutions was less than 10%. Rate in 35 institutions was from 10% to less than 20%. Rate in 7 institutions was equal to or over 20%. Out of 1,113 children examined twice, 28 (2.5%) children were positive consecutively, 53 (4.8%) were positive with negative conversion, 47 (4.2%) were negative with positive conversion, and 985 (88.5%) were consecutively negative. It means that in the low endemic area of enterobiasis with around 10% positive rate, the two consecutive examinations may increase the egg detection rate of 4.2-4.8%. The small number of consecutive egg positive children also suggests that the worm burden of the positive children might be low. Since the egg positive rate of that age group in this City increased from 1.85% (1997), and 3.0% (1998), the more intensive regular control should be executed.     

Status of intestinal helminthic infections of borderline residents in North Korea

The present authors investigated intestinal parasitic infections among North Korean residents and refugees in China in 2003. The Kato-Katz method was applied to 236 residents and soldiers in a town on the North Korea-China border and to 46 people at a refugee camp in China. Only eggs of Ascaris and Trichuris were detected, with egg positive rates of 41.1% and 37.6%, respectively. The total egg positive rate was 55.0% and most of those who were egg positive were only lightly infected. Women of 61.2% and men of 53.1% were egg positive. The refugees from rural areas showed higher egg positive rates than those from urban areas. The present investigation confirmed high prevalence of soil-transmitted intestinal helminths in rural borderline areas of North Korea.     

Flow Cytometric Analysis and Sorting of Heterodera glycines Eggs

A nondestructive technique was developed to characterize and separate eggs of soybean cyst nematode, Heterodera glycines, by developmental stage using flow cytometry. Eggs from cysts cultured on susceptible soybean roots were suspended in 0.1% xanthan gum or 59% sucrose and loaded into either a Coulter EPICS 752 or EPICS 753 flow cytometer. Eggs were analyzed and sorted according to forward angle and 90° light scatter, flow cytometric parameters that are relative measures of object size and granularity, respectively. Mature eggs containing vermiform juveniles were less granular and slightly larger than eggs in earlier stages of embryogeny, allowing for separation of mature eggs from immature eggs. The effectiveness of flow cytometric sorting was evaluated by comparing the developmental stages of subpopulations of unsorted and sorted eggs. Of a subpopulation of unsorted eggs, 62% contained vermiform juveniles, whereas 85 to 95% of sorted subpopulations of larger, less granular eggs contained vermiform juveniles. Suspending H. glycines eggs in 0.1% xanthan gum or 59% sucrose for flow cytometric analysis had no effect on subsequent egg hatch in vitro. This technique is an efficient and effective means to collect large, relatively homogeneous quantities of H. glycines eggs in early or late embryogeny, and would likely be useful for analyzing and sorting eggs of other nematode species for use in developmental, genetic, or physiological research, or for identification and collection of parasitized eggs.     

Egg positive rate of Enterobius vermicularis and Taenia spp. by cellophane tape method in primary school children in Sivas, Turkey

The aim of the present study was to find out the number of students with enterobiasis and/or taeniasis in primary schools of Sivas. Among the 2,029 students in 6 primary schools, 316 (15.6%) were positive to Enterobius vermicularis eggs and 32 (1.6%) were positive to Taenia spp. eggs by the cellophane tape method. The egg positive rates of E. vermicularis and Taenia spp. ranged from 9.4% to 27.2% and from 0.8% to 2.6% respectively among six schools. The egg positive rate of E. vermicularis was found to be significantly different among these schools (chi2 = 31.96, P < 0.05), whereas there was no significant difference between the schools for Taenia spp. (chi2 = 4.37; P > 0.05). The rate (18.7%) of E. vermicularis in the urban slum regions was higher than the rate (11.5%) in the urban central regions (chi2 = 19.20; P < 0.05). Above results demonstrate that the egg positive rate of E. vermicularis and Taenia spp. was still prevalent among primary school children.     

Effects of Some Pesticides on Development of Ascaris suum Eggs

To evaluate the effects of pesticides to parasite eggs, Ascaris suum eggs were incubated with 5 different pesticides (1:1,500-1:2,000 dilutions of 2% emamectin benzoate, 5% spinetoram, 5% indoxacarb, 1% deltamethrin, and 5% flufenoxuron; all v/v) at 20℃ for 6 weeks, and microscopically evaluated the egg survival and development on a weekly basis. The survival rate of A. suum eggs incubated in normal saline (control eggs) was 90±3% at 6 weeks. However, the survival rates of eggs treated with pesticides were 75-85% at this time, thus significantly lower than the control value. Larval development in control eggs commenced at 3 weeks, and 73±3% of eggs had internal larvae at 6 weeks. Larvae were evident in pesticide-treated eggs at 3-4 weeks, and the proportions of eggs carrying larvae at 6 weeks (36±3%-54±3%) were significantly lower than that of the control group. Thus, pesticides tested at levels similar to those used in agricultural practices exhibited low-level ovicidal activity and delayed embryogenesis of A. suum eggs, although some differences were evident among the tested pesticides.     

Evidence of female cryptic choice in crayfish

To test whether male body size affects female reproductive investment in the polygamous crayfish Procambarus clarkii, we described mating behaviour of virgin females paired with either small or large males, and analysed the number, size and weight of both eggs and juveniles sired by either types of male. Along with confirming the overt selection by females of larger mates, we found that the size and weight of both the eggs and the juveniles were higher when sired by larger fathers. This suggests that P. clarkii females exert a form of cryptic choice for large males, seemingly adjusting the quantity of egg deutoplasm in function of the mate body size. The question of why females spend time and energy to brood low-fitness offspring is finally raised.     

Infection rates of Enterobius vermicularis and Clonorchis sinensis of primary school children in Hamyang-gun, Gyeongsangnam-do (province), Korea.

The egg positive rate of Enterobius vermicularis and Clonorchis sinensis of school children in the rural area was studied in Hamyang-gun, Gyeongsangnam-do in Korea. Cellotape anal swab and formalin ether concentration methods were performed one time to 720 primary school children. The total egg positive rate of E. vermicularis was 12.6% in two schools (Baekjeon and Wiseong). In the Baekjeon and Wiseong primary school, the egg positive rate of E. vermicularis was 4.6% and 13.4%, respectively. Pinworm egg positive rate was 17.6% in the lower grades (1st, 2nd and 3rd), and 7.7% in higher grades (4th, 5th and 6th). The total egg positive rate of male and female was 12.6% and 12.7%, respectively. The egg positive rate of C. sinensis of Baekjeon and Wiseong primary school was 1.5% and 0.46%, respectively. The total egg positive rate of C. sinesis was 0.56%. This survey showed that continuous education and chemotherapy is necessary to treat and prevent reinfection of E. vermicularis. In the case of C. sinensis, health education for school children is recommended to prevent potential infection of adolescents.     

Schistosoma mekongi: a prominent neutrophil chemotactic activity of egg antigen with reference to that of Schistosoma japonicum

Schistosoma mekongi causes granulomatous lesions around eggs deposited in the liver with neutrophil-rich inflammatory reactions in the early stage of the egg laying. To define the aspects of the typical pathogenesis of S. mekongi infection, we determined the difference between soluble egg antigen (SEA) from S. mekongi and S. japonicum with a focus on chemotactic factors for neutrophils or eosinophils. Mean volume and protein amount of S. mekongi eggs was 71 and 58% of those of Schistosoma japonicum eggs, respectively. Neutrophil chemotactic activity of S. mekongi SEA was about two times higher than that of S. japonicum. In contrast, eosinophil chemotactic activity of S. mekongi SEA was about half of that of S. japonicum SEA. Molecular analysis revealed that S. mekongi SEA contains higher molecular-weight components with a lower level of glycosylation, and this is likely to be related to the intense neutrophil chemotactic activity in comparison with S. japonicum SEA. The prominent chemotactic reactivity for neutrophils is likely to be involved in the typical pathogenesis of mekongi schistosomiasis.     

The intimate genetics of Drosophila fertilization

The union of haploid gametes at fertilization initiates the formation of the diploid zygote in sexually reproducing animals. This founding event of embryogenesis includes several fascinating cellular and nuclear processes, such as sperm–egg cellular interactions, sperm chromatin remodelling, centrosome formation or pronuclear migration. In comparison with other aspects of development, the exploration of animal fertilization at the functional level has remained so far relatively limited, even in classical model organisms. Here, we have reviewed our current knowledge of fertilization in Drosophila melanogaster, with a special emphasis on the genes involved in the complex transformation of the fertilizing sperm nucleus into a replicated set of paternal chromosomes.     

First fossil gravid turtle provides insight into the evolution of reproductive traits in turtles

Here we report on the first discovery of shelled eggs inside the body cavity of a fossil turtle and on an isolated egg clutch, both referable to the Cretaceous turtle Adocus. These discoveries provide a unique opportunity to gain insight into the reproductive traits of an extinct turtle and to understand the evolution of such traits among living turtles. The gravid adult and egg clutch indicate that Adocus laid large clutches of rigid-shelled spherical eggs and established their nests near rivers, traits that are shared by its closest living relatives, the soft-shelled turtles. Adocus eggshell, however, was probably more rigid than that of living turtles, based on its great thickness and structure, features that may represent unique adaptations to intense predation or to arid nest environments. In light of the reproductive traits observed in Adocus, the distribution of reproductive traits among turtles reveals that large clutches of rigid-shelled eggs are primitive for hidden-necked turtles (cryptodirans) and that spherical eggs may have evolved independently within this group.