Impacts of HAB species Heterosigma akashiwo on early development of the scallop Argopecten irradians Lamarck

The effects of Heterosigma akashiwo on the early development of Argopecten irradians Lamarck: eggs, D-shaped larvae, eye-spot larvae and juveniles, were investigated under laboratory conditions. Exposing fertilized eggs to various densities of H. akashiwo algal culture revealed that the development of the embryos to the gastrula was significantly slowed at densities of more than 1 X 10(4) cells/ml algal cells, and mostly was arrested when the embryos reached the trochophore larvae stage. At this stage, several trochophore larvae were adhered together by the algal cells, resulting in the inhibition of their swimming activity. Larvae had still not developed into D-shaped larvae after 30 h, and therefore did not finish the hatching process. The attachment and adherence of the algal cells to the larvae might be an important process in the mechanism of the impact on egg hatching success. The activity of the D-shaped larvae was significantly inhibited after 48 h exposure to H. akashiwo at a density of 15 X 10(4) cells/ml and after 96 h at 10 X 10(4) cells/ml. The survival rate of the eye-spot larvae was decreased significantly after 48 h exposure to the algal culture at densities of more than 1 X 10(4) cells/ml. However, all the juveniles could survive and their climbing and attachment activity were not affected after 1 and 5 h exposure to the algal culture at all the various algal cell densities tested from 5 to 20 X 10(4) cells/ml. The results indicated that susceptibility of embryos or larvae to the alga H. akashiwo differs depending on the developmental stage. The embryos and the eye-spot larvae of A. irradians are more sensitive stages to the toxicity of H. akashiwo. Observed effects of H. akashiwo exposure on early development of A. irradians serve to point out to the potential danger of this alga for scallop populations. The possible toxicological mechanisms of H. akashiwo on the scallop embryos and larvae are discussed. (c) 2005 Elsevier B.V All rights reserved.

Genetic parameter estimates for growth traits at early stage of Pacific abalone, Haliotis discus hannai Ino

Heritability and genetic and phenotypic correlations were estimated for juvenile growth traits of Pacific abalone Haliotis discus hannai Ino. The estimates were calculated from shell length and shell width measurements on progeny resulting from 12 half-sib families and 36 full-sib families obtained using artificial fertilization of mating three females to each male. The measurements were taken at 10, 20 and 30 d after fertilization. It was found that heritability estimates based on sire component ranged from 0.23 to 0.36 for shell length and 0.21 to 0.32 for shell width. Heritability estimates from dam component were larger than those from sire component at three ages, indicating presence of maternal effects, non-additive genetic effects and common environmental effects. Phenotypic correlations were significant at three ages (P < 0.05), with values of 0.92, 0.93 and 0.92, respectively. Genetic correlations from the paternal half-sib correlation analysis were highly positive at three ages, with values of 0.50, 0.78 and 0.81, respectively. The results suggest that selective breeding is an effective approach to improving growth traits of Pacific abalone stocks.

北京中小学生创造性思维的发展以及十三年前后之比较

This study investigated the major characteristics of creative thinking development for the school children in Beijing with paper/pencil tests. The “Creative Thinking Test” was executed. The representative samples were two groups of students who came from the classes in 3rd-grade to 12th-grade of normal schools in Beijing. The classes were selected at random, one grade one class. One group is composed of 387 students (218 males, 169 females) in 1993, the other is composed of 420 students (181 males, 239 females) in 2006. According to the data analysis, the major characteristics and the changes over the 13 years of the development of creative thinking for student were explored and discussed. 1) The development trends of three types of creative thinking were all flexuous increase with grade moving up. The mean score of elementary school students was the lowest. And scores of junior high school students and senior high school students were significant higher than elementary school students’. 2) The most rapid increase occurred from the 5th grade to 6th grade. 3) Slumps occurred in the 7th grade in PNE curve and also in the 9th and 12th grades in TPC curves. There was no slump in FGA curve. 4) The girl’s scores in PNE and TPC tests were significant better than boys’. No obvious gender difference was found in FGA test. 5) The scores of three creative thinking tests in 2006 were all better than those in 1993. Separately, the scores of FGA and TPC tests in 2006 were significant higher than the corresponding scores in 1993, and no significant difference was found in two PNE tests. 6) There was no significant difference in the maximum scores of the three creative thinking tests between 2006 and 1993. 7) The most rapid developing period of three types of creative thinking in 2006 were the 5th grade and the 6th grade. The same period in 1993 was from the 7th grade to 9th grade. 8) In 1993, there is no significant gender difference for each creative thinking test. In 2006, PNE and TPC results had remarkable gender difference that girls were higher than boys. No significant gender difference was found in FGA tests.

High resolution time-of-flight spectrometer for crossed molecular beam study of elementary chemical reactions

In this article, we describe an apparatus in our laboratory for investigating elementary chemical reactions using the high resolution time-of-flight Rydberg tagging method. In this apparatus, we have adopted a rotating source design so that collision energy can be changed for crossed beam studies of chemical reactions. Preliminary results on the HI photodissociation and the F atom reaction with H-2 are reported here. These results suggest that the experimental apparatus is potentially a powerful tool for investigating state-to-state dynamics of elementary chemical reactions. (c) 2005 American Institute of Physics.