Photosynthetic parameters of sexually different parts of Porphyra katadai var. hemiphylla (Bangiales, Rhodophyta) during dehydration and re-hydration

Physiological data from extreme habitat organisms during stresses are vital information for comprehending their survival. The intertidal seaweeds are exposed to a combination of environmental stresses, the most influential one being regular dehydration and re-hydration. Porphyra katadai var. hemiphylla is a unique intertidal macroalga species with two longitudinally separated, color distinct, sexually different parts. In this study, the photosynthetic performance of both PSI and PSII of the two sexually different parts of P. katadai thalli during dehydration and re-hydration was investigated. Under low-grade dehydration the variation of photosystems of male and female parts of P. katadai were similar. However, after the absolute water content reached 42%, the PSI of the female parts was nearly shut down while that of the male parts still coordinated well and worked properly with PSII. Furthermore, after re-hydration with a better conditioned PSI, the dehydrated male parts were able to restore photosynthesis within 1 h, while the female parts did not. It is concluded that in P. katadai the susceptibility of photosynthesis to dehydration depends on the accommodative ability of PSI. The relatively lower content of phycobiliprotein in male parts may be the cause for a stronger PSI after severe dehydration.

Estimates of genetic parameters for growth traits of the sea urchin, Strongylocentrotus intermedius

Heritabilities and genetic and phenotypic correlations were estimated for body weight, test diameter, and test height of the sea urchin from measurements on progeny resulting from 11 sires and 33 dams by artificial fertilization of 3 females by single males, and measurements at 8, 10, and 12 months after metamorphism. Point estimate for heritabilities based on the sire components of variance were moderate to high for body weight (0.21-0.49), test diameter (0.21-0.47), and test height (0.22-0.37). Genetic correlations were significant for body weight with test diameter (0.30similar to0.65) and test height (0.30similar to0.54) and test diameter with test height (0.31similar to0.65). Genetic correlation estimates, derived the nested design and half-sib correlation analysis used in this study, appear to provide reliable estimates. Significant phenotypic correlations were found for body weight with test diameter (0.82similar to0.86) and test height (0.49similar to0.83), and test diameter with test height (0.47similar to0.84). The phenotypic correlations for test height with body weight (0.491) and test diameter (0.467) at 12 months' of age were smaller than those earlier sampling periods.(C) 2004 Published by Elsevier B.V.

Assessment of genetic diversities of selected Laminaria (Laminariales, Phaeophyta) gametophytes by inter-simple sequence repeat analysis

Inter-simple sequence repeat (ISSR) analysis was used to assess genetic diversity among 10 pairs of male and female Laminaria gametophytes. A total of 58 amplification loci was obtained from 10 selected ISSR primers, of which 34 revealed polymorphism among the gametophytes. Genetic distances were calculated with the Dice coefficient ranging from 0.006 to 0.223. A dendrogram based on the unweighted pair-group method arithmetic (UPGMA) average showed that most male and female gametophytes of the same species were clustered together and that 10 pairs of gametophytes were divided into four groups. This was generally consistent with the taxonomic categories. The main group consisted of six pairs of gametophytes, which were selected from Laminaria japonica Aresch. by intensive inbreeding through artificial hybridization. One specific marker was cloned, but was not converted successfully into a sequence characterized amplified region (SCAR) marker. Our results demonstrate the feasibility of applying ISSR markers to evaluate Laminaria germplasm diversities.

Quantitative traits correlative analysis and growth comparison among different populations of bay scallop, Argopecten irradians

The shell traits and weight traits are measured in cultured populations of bay scallop, Argopecten irradians. The results of regression analysis show that the regression relationships for all the traits are significant (P < 0.01). The correlative coefficients between body weight, as well as tissue weight with shell length, shell height and shell width are significant (P < 0.05). But the correlative coefficients between the anterior and posterior auricle length with body weight as well as tissue weight are not significant (P > 0.05). The multiple regression equation is obtained to estimate live body weight and tissue weight. The above traits except anterior and posterior auricle length are used for the growth and production comparison among three cultured populations, Duncan's new multiple range procedure analysis shows that all the traits in the Lingshuiqiao (LSQ) population are much more significant than those of the other two populations (P < 0.01), and there is no significant difference between the Qipanmo (QPM) and Dalijia (DLJ) populations in all traits (P > 0.05). The results indicate that the LSQ population has a higher growth rate and is expected to be more productive than the other two populations.

DNA fingerprinting of selected Laminaria (Phaeophyta) gametophytes by RAPD markers

Random amplified polymorphism DNA (RAPD) analysis was applied to germplasm characterization in 33 different selected Laminaria male and female gametophytes. The positional homology of the RAPD analysis using sequence characterized applied region (SCAR) method was successfully conducted. A total of 233 polymorphic loci were obtained from 18 selected primers after screening, of which 27 stable and clear bands were selected to construct a fingerprint map for discrimination of each gametophyte. Seven RAPD markers from five primers were finally determined by a computer program to construct the fingerprint map. Three specific markers closely related with gametophytes were obtained and were converted to gametophytic SCAR markers, the first SCAR marker report on Laminaria germplasm and applicable to cultivars identification. These results demonstrated the feasibility of applying RAPD markers to germplasm characterization in selected Laminaria gametophytes, and can provide a molecular basis for breeding new Laminaria strains. (C) 2004 Elsevier B.V. All rights reserved.

In vitro selected peptides bind with thymidylate synthase mRNA and inhibit its translation

Thymidylate synthase (TS), an essential enzyme for catalyzing the biosynthesis of thymidylate, is a critical therapeutic target in cancer therapy. Recent studies have shown that TS functions as an RNA-binding protein by interacting with two different sequences on its own mRNA, thus, repressing translational efficiency. In this study, peptides binding TS RNA with high affinity were isolated using mRNA display from a large peptide library (>10(13) different sequences). The randomized library was subjected up to twelve rounds of in vitro selection and amplification. Comparing the amino acid composition of the selected peptides (12th round, R12) with those from the initial random library (round zero, R0), the basic and aromatic residues in the selected peptides were enriched significantly, suggesting that these peptide regions might be important in the peptide-TS mRNA interaction. Categorizing the amino acids at each random position based on their physicochemical properties and comparing the distributions with those of the initial random pool, an obvious basic charge characteristic was found at positions 1, 12, 17 and 18, suggesting that basic side chains participate in RNA binding. Secondary structure prediction showed that the selected peptides of R12 pool represented a helical propensity compared with R0 pool, and the regions were rich in basic residues. The electrophoretic gel mobility shift and in vitro translation assays showed that the peptides selected using mRNA display could bind TS RNA specifically and inhibit the translation of TS mRNA. Our results suggested that the identified peptides could be used as new TS inhibitors and developed to a novel class of anticancer agents.

Identification of quantitative trait loci for growth-related traits in the Pacific abalone Haliotis discus hannai Ino

The locations and effects of quantitative trait loci (QTL) were estimated for nine characters for growth-related traits in the Pacific abalone (Haliotis discus hannai Ino) using a randomly amplified polymorphic DNA (RAPD), amplification fragment length polymorphism (AFLP) and SSR genetic linkage map. Twenty-eight putatively significant QTLs (LOD > 2.4) were detected for nine traits (shell length, shell width, total weight, shell weight, weight of soft part, muscle weight, gonad and digestive gland weight, mantle weight and gill weight). The percentage of phenotypic variation explained by a single QTL ranged from 8.0% to 35.9%. The significant correlations (P < 0.001) were found among all the growth-related traits, and Pearson's correlation coefficients were more than 0.81. For the female map, the QTL for growth were concentrated on groups 1 and 4 linkage maps. On the male map, the QTL that influenced growth-related traits gathered on the groups 1 and 9 linkage maps. Genetic linkage map construction and QTL analysis for growth-related traits are the basis for the marker-assisted selection and will eventually improve production and quality of the Pacific abalone.

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.

Inbreeding depression for various traits in two cultured populations of the American bay scallop, Argopecten irradians irradians Lamarck (1819) introduced into China

This paper examines the effect of inbreeding level of population on the magnitude of inbreeding depression expressed by comparing them between two cultured populations (A and B) in the hermaphroditic animal of the bay scallop Argopecten irradians irradians. Population A is expected to have less genetic variations and higher inbreeding level due to longer cultured history (20 generations) and less "ancestral" individuals (26 individuals) than population B due to shorter cultured history (4 generations) and more "ancestral" individuals (406 individuals). Two groups within each population were produced, one using self-fertilization and one using mass-mating within the same population. Selfed offspring (AS and BS) from two populations both had lower fitness components than their mass-mated counterparts (AM and BM) and exhibited inbreeding depression for all examined traits, e.g. lower hatching, less viability and slower growth, indicating that inbreeding depression is a common feature in this animal. Fitness components in all traits of offspring from population A significantly differed those from population B and the magnitude of inbreeding depression for all traits in population A with higher inbreeding level was significantly smaller than that in population B with lower inbreeding level, indicating that both fitness components and magnitude of inbreeding depression were significantly affected by inbreeding level of populations and genetic load harbored in population A may be partially purged through inbreeding. Moreover, the magnitude of inbreeding depression in the two populations both varied among traits and life history stages. The present results support the partial-dominance hypothesis of inbreeding depression. (C) 2008 Elsevier B.V. All rights reserved.

Decline in medicinal and forage species with warming is mediated by plant traits on the Tibetan Plateau

Experimental studies of how global changes and human activities affect plant diversity often focus on broad measures of diversity and discuss the implications of these changes for ecosystem function. We examined how experimental warming and grazing affected species within plant groups of direct importance to Tibetan pastoralists: medicinal plants used by humans and palatable plants consumed by livestock. Warming resulted in species losses from both the medicinal and palatable plant groups; however, differential relative vulnerability to warming occurred. With respect to the percent of warming-induced species losses, the overall plant community lost 27%, medicinal plants lost 21%, and non-medicinal plants lost 40% of species. Losses of palatable and non-palatable species were similar to losses in the overall plant community. The deep-rootedness of medicinal plants resulted in lowered sensitivity to warming, whereas the shallow-rootedness of non-medicinal plants resulted in greater sensitivity to warming; the variable rooting depth of palatable and non-palatable plants resulted in an intermediate response to warming. Predicting the vulnerability of plant groups to human activities can be enhanced by knowledge of plant traits, their response to specific drivers, and their distribution within plant groups. Knowledge of the mechanisms through which a driver operates, and the evolutionary interaction of plants with that driver, will aid predictions. Future steps to protect ecosystem services furnished by medicinal and palatable plants will be required under the novel stress of a warmer climate. Grazing may be an important tool in maintaining some of these services under future warming.

Stable carbon isotope analyses show dominance of C3 grasses in the feed selected by small herbivores at the alpine meadow at the Tibetan Plateau

Muscle samples were collected from small herbivorous mammals (Ochotona curzoniae, Microtus oecnomus, Myospalax fontanierii and Lepus oiostolus) at the alpine meadow ecosystem at the Tibetan Plateau in order to address variability in stable carbon isotope composition. Stable carbon isotope values of muscles remain steady and show no significant variations (-25.72 to -27.04 parts per thousand) among the four small mammal species. Based on the mass balance theory of stable isotopes, it is proposed that small herbivorous mammals mainly (or totally) rely on C3 grasses as food supply, and there is few or no distribution of C4 grasses at the ecosystem. The results reflect our previous study on the isotope patterns of plant species. Thus, stable carbon isotope analysis of muscles provides a method to address dietary selection and dietary variability in herbivores. In addition, stable carbon isotopic analyses can be used to address changes in vegetation distributions in ecosystem and paleovegetaion and paleoclimate.

人口空间数据误差分析研究

Spatial population data, obtained through the pixeling method, makes many related researches more convenient. However, the limited methods of precision analysis prevent the spread of spatial distribution methods and cumber the application of the spatial population data. This paper systematically analyzes the different aspects of the spatial population data precision, and re-calculates them with the reformed method, which makes breakthrough for the spread of the pixeling method and provides support and reference for the application of spatial population data. The paper consists of the following parts: (2) characters of the error; (2) origins of the error; (3) advancement on the calculating methods of the spatial population data. In the first place, based on the analysis of the error trait, two aspects of the spatial population data precision are characterized and analyzed: numerical character and spatial distributing character. The later one, placed greater emphasis on in this paper, is depicted in two spatial scales: county and town. It is always essential and meaningful to the research in this paper that spatial distribution is as important as numerical value in analyzing error of the spatial distributed data. The result illustrates that the spatial population data error appears spatially in group, although it is random in the aspect of data statistics, all of that shows there lies spatial systematic error. Secondly, this paper comes to conclude and validate the lineal correlation between the residential land area (from 1:50000 map and taken as real area) and population. Meanwhile, it makes particular analysis on the relationship between the residential land area, which is obtained from the land use map and the population in three different spatial scales: village, town and county, and makes quantitative description of the residential density variation in different topological environment. After that, it analyzes the residential distributing traits and precision. With the consideration of the above researches, it reaches the conclusion that the error of the spatial distributed population is caused by a series of factors, such as the compactness of the residents, loss of the residential land, the population density of the city. Eventually, the paper ameliorates the method of pixeling the population data with the help of the analysis on error characters and causes. It tests 2-class regionalization based on the 1-class regionalization of China, and resorts the residential data from the land use map. In aid of GIS and the comprehensive analysis of various data source, it constructs models in each 2-class district to calculate spatial population data. After all, LinYi Region is selected as the study area. In this area, spatial distributing population is calculated and the precision is analyzed. All it illustrates is that new spatial distributing population has been improved much. The research is fundamental work. It adopts large amounts of data in different types and contains many figures to make convincing and detailed conclusions.