Quantitative Analysis of Protein Synthesis Altered by Estrogen in Cultured Xenopus Liver Parenchymal Cell

Using the primary culture system of male Xenopus laevis hepatocytes consisting of more than 95% parenchymal cells, the effect of estradiol-17 β (10⁻⁶M) on protein synthesis was quantitatively analyzed by ³H-leucine incorporation kinetics and the estimation of specific radioactivity of newly synthesized secretory protein. The cells in a well defined culture revealed high plating efficiency and very low DNA synthetic activity. The cultured cells could synthesize several secretory proteins containing serum albumin. The pattern of secreted proteins in SDS-polyacrylamide gel electrophoresis (SDS-PAGE) did not alter with culture time but secretion rate of protein increased for 7 days, starting on the third day following inoculation. Estradiol added to the culture media extensively induced the synthesis of yolk precursor protein vitellogenin which accounted for 40–50% of the overall secretory protein synthesis and 20–30% of the total protein synthesis on day 7 of estradiol treatment. Ultimately, the total protein synthesis and secretory protein synthesis were stimulated 1.2–1.3 fold and 2.0–2.2 fold, respectively, over those of the control cells cultured in the absence of estradiol. These results indicated that the stimulation of protein synthesis was largely due to vitellogenin production. Such an estradiol-dependent stimulation of protein synthesis was also detected in the low molecular weight protein(s). On the other hand, albumin synthesis was evidently reduced by estradiol. Thus, estradiol had two different effects on protein synthesis.
The results obtained in this study will be discussed in relation to the findings o in vivo experiments.     

LIFE HISTORY OF FRASER'S DOLPHIN, LAGENODELPHIS HOSEI, BASED ON A SCHOOL CAPTURED OFF THE PACIFIC COAST OF JAPAN

Life history of Fraser's dolphin, a little known delphinid species, was examined based on 108 specimens from a school captured by the driving fishing method in Japan. The sex ratio was approximately 1:1, and mature dolphins of both sexes formed the bulk of the school. The oldest animals were two males and a female of 17.5 yr. Age and body length at sexual maturity were estimated at 7–10 yr and 220–230 cm in males and 5–8 yr and 210–220 cm in females. Mature males were larger in body length than mature females and showed apparent secondary sexual features: deepening of the tail stock and widening and darkening of the lateral dark stripe. The annual ovulation rate was 0.49. The estimated neonatal length (110 cm) predicts a gestation period of about 12.5 mo and calving peaks in spring and probably also in fall. The calving interval was estimated to be about 2 yr. These life history parameters are similar to those of the striped and pantropical spotted dolphins, except for longevity. The reproductive rate of this species may be lower than that of other pelagic delphinids, if the observed shorter longevity is real.     

CARDIAC MUSCLE CELL DIFFERENTIATION IN VITRO FROM A CHARACTERISTIC CELL LINE ISOLATED FROM MOUSE TERATOCARCINOMA

A characteristic in vitro cell line, SEBIII, was isolated from the mouse teratocarcinoma OTT6050. The SEBIII line, which maintains the structure of the embryoid body, grows rapidly in suspension culture. The chromosome number is near diploid. SEBIII cells, which were transferred to the peritoneal cavity of 129/Sv strain mice and left for one week, differentiated into several tissues in the subsequent in vitro culture. Of the tissues differentiated, the most dominant was the spontaneously pulsating muscle cells. Electron microscopic observations of these muscle cells revealed the presence of myofilaments with Z bands and intercalated disks. The nature of the factor(s) which induce the differentiation of SEBIII EB into cardiac muscle cells is discussed.     

Effects of selected insecticides on Diadegma semiclausum（Hymenoptera： Ichneumonidae） and Oomyzus sokolowskii （Hymenoptera： Eulophidae）, parasitoids of Plutella xylostella （Lepidoptera： Plutellidae）

Abstract Field doses of six selected insecticides were tested against the immature (pupae) and mature (adult) stages of Diadegma semiclausum (Hellén) and Oomyzus sokolowskii (Kurdjumov), parasitoids of the diamondback moth, Plutella xylostella (L.). Effects of contact toxicity (direct spraying) of the six insecticides on emergence of parasitoids were found negligible on both species except permethrin which caused 37.5% mortality. All adults of both parasitoid species died 24 hours after exposure to chlorfenapyr, emamectin benzoate and permethrin. In contrast, the three insect growth regulators (IGRs), chlorfluazuron, flufenoxuron and teflubenzuron, were found harmless to both species, and adult mortality of both parasitoid species was 0–16.7%. However, parasitism by the females of both parasitoid species was severely impaired when the females were offered the three IGR diluted solutions for 24 hours. Effects of oral toxicities of the IGRs on longevity of both parasitoids after 12 hours exposure were found to be significantly different between males and females. Compatibility of tested insecticides with D. semiclausum and O. sokolowskii and integration of compatible insecticides with these parasitoids in integrated pest management programs of crucifers are discussed.     

Methods of Predicting Risks of Wheat Damage by White-Fronted Geese

Abstract: Accurately predicting occurrence of wildlife damage is crucial for effective management of problematic wildlife species, because accurate predication allows deterrence efforts to be focused at sites or times where damage is most likely. We explored methods to predict occurrence of white-fronted geese (Anser albifrons) grazing in wheat fields around Lake Miyajimanuma, Japan. Depletion of waste rice grains caused geese to forage on wheat leaves in spring, reducing wheat harvest in grazed fields. The cumulative number of goose-days per hectare of rice-planted area from the beginning of the staging period explained the variation in the proportion of geese foraging in wheat fields. A logistic regression model on the location of vulnerable fields showed that goose grazing was likely to occur in wheat fields far from roads and windbreaks and those close to (within 1,000–2,000 m of) previously grazed fields. Although probability of occurrence of goose grazing was initially low in wheat fields with scaring devices, effectiveness of such devices was lost over the 4 survey years. We recommend farmers in the study area prepare counter-damage measures when the cumulative number of goose-days per rice-planted area approaches a threshold above which some geese are predicted to start foraging on wheat (e.g., 199.46 goose-days/ha rice × 28.95 for 10% of geese foraging on wheat). Further, farmers should be aware that grazing on wheat is more likely to occur if wheat fields within 1,000–2,000 m have already been exploited during that particular season and should concentrate deterrence efforts to wheat fields that are far from roads and windbreaks. Systematic deployment of scaring devices over the entire habitat has a risk of accelerating the decline in effectiveness. Thus, we need methods to retard goose habituation to scaring devices, such as scaring with guns, providing alternative feeding sites, and preventing diet change by geese.     

Establishment of a novel dwarf rat strain: cartilage calcification insufficient (CCI) rats

Rats with dwarfism accompanied by skeletal abnormalities, such as shortness of the limbs, tail, and body (dwarf rats), emerged in a Jcl-derived Sprague-Dawley rat colony maintained at the Institute for Animal Experimentation, St. Marianna University Graduate School of Medicine. Since the dwarfism was assumed to be due to a genetic mutation based on its frequency, we bred the dwarf rats and investigated their characteristics in order to identify the causative factors of their phenotypes and whether they could be used as a human disease model. One male and female that produced dwarf progeny were selected, and reproduction was initiated by mating the pair. The incidence of dwarfism was 25.8% among the resultant litter, and dwarfism occurred in both genders, suggesting that it was inherited in an autosomal recessive manner. At 12 weeks of age, the body weights of the male and female dwarf rats were 40% and 57% of those of the normal rats, respectively. In soft X-ray radiographic and histological examinations, shortening and hypoplasia of the long bones, such as the tibia and femur, were observed, which were suggestive of endochondral ossification abnormalities. An immunohistochemical examination detected an aggrecan synthesis disorder, which might have led to delayed calcification and increased growth plate thickening in the dwarf rats. We hypothesized that the principal characteristics of the dwarf rats were systemically induced by insufficient cartilage calcification in their long bones; thus, we named them cartilage calcification insufficient (CCI) rats.     

Longitudinal changes in δ13C of riffle macroinvertebrates from mountain to lowland sections of a gravel‐bed river

Summary 1. To understand longitudinal changes in the trophic base of benthic macroinvertebrates from mountain to lowland river sections, we investigated carbon stable isotopic compositions (δ¹³C) of macroinvertebrates and their food resources in riffles for four seasons at 14 sites along the main stem of the Toyo River, Japan. 2. At each site, δ¹³C was usually highest or nearly highest for periphyton (epilithic biofilm) and was lowest for transported leaf materials. Among macroinvertebrate groups, grazers usually had higher δ¹³C values than filterers or predators. 3. During all seasons, δ¹³C of periphyton and all macroinvertebrate groups increased downstream from mountain to upland sections, but decreased downstream from upland to lowland sections. In addition, the difference between grazer δ¹³C and filterer δ¹³C decreased from mountain to upland sections, but increased from upland to lowland sections. 4. The observed changes in δ¹³C of periphyton and macroinvertebrates from mountain to upland sections agree with previous reports: the δ¹³C of periphyton and consumers increased with stream size and productivity. The decrease in δ¹³C of periphyton and macroinvertebrates from upland to lowland sections has not been reported previously, and this may have resulted from an increased importance of terrestrial detritus relative to periphyton production in the lowland section, where riffles were infrequent and pools dominated the reach. 5. A simple mixing model of δ¹³C showed that grazers rely mostly on periphyton at all sites, whereas the importance of periphyton for filterers changed longitudinally increasing from mountain to upland sections and decreasing from upland to lowland sections. This longitudinal trend for filterers is possibly associated with the changes in the availability or quality of terrestrial detritus in transported particulate organic matter. 6. Longitudinal changes in the relative importance of autochthonous production and allochthonous detritus appear to be reflected in δ¹³C of riffle benthic communities. The longitudinal changes were not monotonic, and specific reach characteristics may be responsible for the greater importance of allochthonous detritus in mountain and lowland sections.     

Effects of temperature on the cytokinin requirement of tobacco calluses

A cytokinin-nonrequiring strain (T22) was isolated from a cytokinin-requiringcallus strain T2 of tobacco (Nicotiana tabacum var. Bright Yellow). Strain T22 grew rapidly on the medium without added kinetinat 26?C. But its growth was completely suppressed at 16?C. Thisgrowth suppression at 16?C was partially recoverable by supplyingkinetin. Benzyladenine, geranylaminopurine and 2-methyl-8-benzylamino-s-triazolo[l,5-a]pyrazinewere also effective in removing growth suppression at 16?C.Adenine, which was unable to remove growth suppression of T22at 16?C, promoted the growth of T2 at 26?C, but not at 16?C.Physiological differences between cytokinin-requiring and -nonrequiringcalluses are discussed. ¹Part II in the series "Studies, on Plant Tissue Cultures";for Part I, See Plant & Cell Physiol. 9: 103–114 (1968). (Received May 29, 1970; )