Isolation and characterization of microsatellite DNA markers from mangrove crab,Scylla paramamosain

The first five variable microsatellite DNA loci for mangrove crab, Scylla paramanosain, were developed. Allelic variation and other characteristics at these loci were examined in this species captured at the Urado Bay, Japan. The number of alleles per locus ranged from 24 to 44. The expected heterozygosity across loci ranged from 0.900 to 0.999 and probability of identity (P_I) ranged from 2.8 × 10^?3 to 1.7 × 10^?2. Therefore, these microsatellite markers could be useful for estimating effect of stock enhancement release and population genetic structure of mangrove crab.     

THE CENTRAL ROLE OF THE GENITAL DUCT IN THE DEVELOPMENT AND REGENERATION OF THE GENITAL ORGANS IN THE SEA URCHIN

Formation and regeneration of the genital papilla in the sea urchin, Hemicentrotus pulcherrimus were studied to find out what factor(s) control expression of the secondary sexual characters in the papilla. Surgical removal of various regions of the genital organ and the blood vessels was performed separately or in various combinations. The proximal part of the genital duct or its rudiment (D2 region) plays an essential role in the formation or regeneration of the papilla, and in the establishment of its sexual characters as well, i.e., if the D2 region is removed, papilla formation or regeneration is completely suppressed; when the D2 region is left uninjured, the papilla develops and displays the sexual characters even in the absence of the gonad, the distal part of the duct, a blood supply to the D2 region or all three of them combined. It can be concluded that the proximal part of the genital duct carries the factor(s) for determination and expression of the secondary sexual characters in the genital papilla. Discussion has been made about what factor(s) can be considered to reside within the cells of the D2 region of the duct.     

Up‐regulation of Tyrosinase Gene by Nitric Oxide in Human Melanocytes

Ultraviolet light (UV) radiation causes skin‐tanning, which is thought to be mediated by stimulating the release of melanogenic factors from keratinocytes as well as other cells. Nitric oxide (NO) has been reported to be generated after UV radiation and to stimulate melanocytes as one of the melanogens. In a previous experiment by another group on melanogenesis induced by NO, increases in both tyrosinase activity and tyrosinase protein levels were observed after daily stimulation of NO for 4 days. In the present study, we investigated tyrosinase gene expression within the first 24 hr of NO‐induced melanogenesis. Tyrosinase mRNA expression was found to be induced 2 hr after a single treatment with S‐nitroso‐N‐acetyl‐ l ‐arginine. An increase of tyrosinase activity was also detected time‐dependently within the 24‐hr period, accompanied by an increase of tyrosinase protein levels. The induction of mRNA expression was suppressed by a cyclic guanosine 3′,5′‐monophosphate (cGMP)‐dependent protein kinase (cGMP/PKG) inhibitor. These results suggest that the enhancement of tyrosinase gene expression via the cGMP pathway may be a primary mechanism for NO‐induced melanogenesis.     

Oviposition habits of a univoltine blackfly, Prosimulium kiotoense (Diptera: Simuliidae), in Kyushu, Japan

Oviposition habits of a univoltine mammalophilic blackfly, Prosimulium kiotoense Shiraki, were investigated at a stream in Kyushu Island, Japan. The flies oviposited on bryophyte mosses growing on river bank rock surfaces. The eggs were laid singly, but large irregular egg masses were often formed because many females oviposited within the same small areas. Wet sites with dense bryophyte cover at heights between 0 and 15 cm above water level were selected for oviposition. Oviposition activity was observed in the latter half of April. P. kioteonse females came to the site to lay eggs after 11.00 hours in the morning, when air temperature rose to about 15 degrees C. Peak ovipositional activity occurred between 12.00 and 14.00 hours.     

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.     

Heteroses in Net Photosynthetic Rate, Leaf Area, Tillering, and Some Physiological Characters of 35 F1 Rice Hybrids

Net photosynthetic rate, leaf area, tillering, shoot weight,and leaf area ratio for 35 F₁ rice (Oryza sativa L.) hybridsduring the vegetative stage were compared with correspondingvalues for parental varieties. Shoot weight and leaf area showedheterosis. However, hybrid vigour was not reflected in net photosyntheticrate. Leaf area was closely correlated with heteroses in shootdry weight and tillering. Thus F₁ rice hybrids grow vigorouslybecause of their high leaf area development, which is causedby high tillering. Key words: F₁ rice hybrid, Net photosynthetic rate, Leaf area     

The land–atmosphere water flux in the tropics

Tropical vegetation is a major source of global land surface evapotranspiration, and can thus play a major role in global hydrological cycles and global atmospheric circulation. Accurate prediction of tropical evapotranspiration is critical to our understanding of these processes under changing climate. We examined the controls on evapotranspiration in tropical vegetation at 21 pan-tropical eddy covariance sites, conducted a comprehensive and systematic evaluation of 13 evapotranspiration models at these sites, and assessed the ability to scale up model estimates of evapotranspiration for the test region of Amazonia. Net radiation was the strongest determinant of evapotranspiration (mean evaporative fraction was 0.72) and explained 87% of the variance in monthly evapotranspiration across the sites. Vapor pressure deficit was the strongest residual predictor (14%), followed by normalized difference vegetation index (9%), precipitation (6%) and wind speed (4%). The radiation-based evapotranspiration models performed best overall for three reasons: (1) the vegetation was largely decoupled from atmospheric turbulent transfer (calculated from Ω decoupling factor), especially at the wetter sites; (2) the resistance-based models were hindered by difficulty in consistently characterizing canopy (and stomatal) resistance in the highly diverse vegetation; (3) the temperature-based models inadequately captured the variability in tropical evapotranspiration. We evaluated the potential to predict regional evapotranspiration for one test region: Amazonia. We estimated an Amazonia-wide evapotranspiration of 1370 mm yr⁻¹, but this value is dependent on assumptions about energy balance closure for the tropical eddy covariance sites; a lower value (1096 mm yr⁻¹) is considered in discussion on the use of flux data to validate and interpolate models.     

Isolation and characterization of microsatellite DNA loci for endangered fish,Japanese huchen (Hucho perryi)

Japanese huchen, Hucho perryi, is an endangered fish in Japan. In order to promote a conservation program for this species, it is necessary to evaluate its genetic diversity and population genetics. For this purpose, we designed 15 primers containing dinucleotide microsatellite regions and examined their allelic variation using a total of 23 wild individuals collected from two different localities. Eight loci showed moderate allelic variation ranging from two to four alleles, with expected heterozygosities from 0.043 to 0.548. These markers will be useful for the assessment of genetic variation for this species.     

ELECTROPHYSIOLOGICAL STUDIES ON NITELLA CELLS, WITH SPECIAL REFERENCE TO THE ELECTRIC RESISTANCE

Electrical properties of Nitella (Tolypella) cells were studied,with special reference to their electric resistance The resistanceof the protoplasm, as well as the potential of the inside ofthe cell, was measured by inserting capillary electrode intothe cell, which had been sealed with vaseline externally atthe middle so that the current across the protoplasm could bereadily determined. The characteristics of the rectification and impedance weremeasured The electric current was found to flow across the protoplasmiclayer more easily from the sap to the external water than inthe reverse direction. The resistance and the capacitance ofthe cell varied with the a.c frequencies used for the measurement Simultaneous measurements were made of the action potential,the action current, and the resistance change of the protoplasmin order to determine the relationship between them An intimateparallelism between the time courses of these three phenomenawas discovered. An attempt was made to interpret the resultsby taking into account the dissociation of ions in the protoplasm. ¹Present address: Japan Atomic Energy Research Institute, Tokai,Ibaraki Prefecture. (Received May 8, 1962; )     

Isolation and characterization of microsatellite DNA loci from the golden cuttlefish,Sepia esculenta Hoyle (Cephalopoda)

The first microsatellite markers were isolated from the golden cuttlefish, Sepia esculenta Hoyle. Eleven primer sets were designed to amplify the marker sequences via polymerase chain reaction. The 45–50 individuals from one wild population in the coastal waters of Ehime Prefecture, Japan were used to screen polymorphism in the 11 microsatellite loci. All the microsatellite loci were polymorphic, with the range of alleles from seven to 27 per locus. The observed and expected heterozygosities ranged from 0.380 to 0.980 and from 0.654 to 0.940, respectively. These marker loci except for one locus showing significant deviation from Hardy–Weinberg equilibrium will be useful for the assessment of genetic variation and population structure of this species.