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941.
The yeast strain (Y18) was isolated from a soil sample collected from Fildes Peninsula, Antarctica. The strain is a psychrophilic yeast with optimum and maximum growth temperatures of 10 ℃ and 18 ℃, respectively. Teliospores were formed after 7 d on malt agar, when the germination of teliospores was observed. Both inositol and D-glucuronate were assimilated. Positive results of the DBB (diazonium blue B) color reaction, urease test, and starch formation were observed. The major CoQ is Qs. All results indicated that Y18 belongs to the genes of Mrakia. The 18S rDNA sequence analyses showed that Y18 is closely related to Mrakiafrigida. DNA-DNA relatedness study, and some biochemistry characteristics indicated that Y18 represents a new species for which Mrakia psychrophila sp. nov. is proposed. 相似文献
942.
The objective of this study is to propose a more accurate and faster MTT 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide colorimetric assay (MCA) for quantitative measurement of polypeptide bacteriocins in solutions with nisin as an example. After an initial incubation of nisin and indicator bacterium Micrococcus luteus NCIB 8166 in tubes, MTT was added for another incubation period. After that, nisin was quantified by estimating the number of viable bacteria based on measuring the amount of purple formazan produced by cleavage of yellow tetrazolium salt MTT. Then MCA was compared to a standard agar diffusion assay (ADA). The results suggested a high correlation coefficient (r2=0.975±0.004) between optical density (OD) and the inhibitory effect of nisin on a bacterial strain Micrococcus luteus NCIB 8166 at a range of 0.125~32 IU/ml. The MCA described in this study was very quick. Quantification of nisin took only 7~8 h and the detection limit was at the level of 0.125 IU/ml when compared to 12 IU/ml and 24~28 h for ADA. The MCA provides an accurate and rapid method for quantifi-cation of nisin in solutions and is expected to be used for quantification of other antimicrobial substances. 相似文献
943.
Pushpendra KG Harindra SB Pawan LK Neeraj K Ajay K Reyazul RM Amita M Jitendra K 《Journal of Zhejiang University. Science. B》2007,8(11):807-814
Quantitative trait loci (QTL) analysis was conducted in bread wheat for 14 important traits utilizing data from four different mapping populations involving different approaches of QTL analysis. Analysis for grain protein content (GPC) sug- gested that the major part of genetic variation for this trait is due to environmental interactions. In contrast, pre-harvest sprouting tolerance (PHST) was controlled mainly by main effect QTL (M-QTL) with very little genetic variation due to environmental interactions; a major QTL for PHST was detected on chromosome arm 3AL. For grain weight, one QTL each was detected on chromosome arms 1AS, 2BS and 7AS. QTL for 4 growth related traits taken together detected by different methods ranged from 37 to 40; nine QTL that were detected by single-locus as well as two-locus analyses were all M-QTL. Similarly, single-locus and two-locus QTL analyses for seven yield and yield contributing traits in two populations respectively allowed detection of 25 and 50 QTL by composite interval mapping (CIM), 16 and 25 QTL by multiple-trait composite interval mapping (MCIM) and 38 and 37 QTL by two-locus analyses. These studies should prove useful in QTL cloning and wheat improvement through marker aided selection. 相似文献
944.
945.
Teachers' education, classroom quality, and young children's academic skills: results from seven studies of preschool programs 总被引:10,自引:0,他引:10
Early DM Maxwell KL Burchinal M Alva S Bender RH Bryant D Cai K Clifford RM Ebanks C Griffin JA Henry GT Howes C Iriondo-Perez J Jeon HJ Mashburn AJ Peisner-Feinberg E Pianta RC Vandergrift N Zill N 《Child development》2007,78(2):558-580
In an effort to provide high-quality preschool education, policymakers are increasingly requiring public preschool teachers to have at least a Bachelor's degree, preferably in early childhood education. Seven major studies of early care and education were used to predict classroom quality and children's academic outcomes from the educational attainment and major of teachers of 4-year-olds. The findings indicate largely null or contradictory associations, indicating that policies focused solely on increasing teachers' education will not suffice for improving classroom quality or maximizing children's academic gains. Instead, raising the effectiveness of early childhood education likely will require a broad range of professional development activities and supports targeted toward teachers' interactions with children. 相似文献
946.
Income is not enough: incorporating material hardship into models of income associations with parenting and child development 总被引:2,自引:0,他引:2
Although research has clearly established that low family income has negative impacts on children's cognitive skills and social-emotional competence, less often is a family's experience of material hardship considered. Using the Early Childhood Longitudinal Study, Kindergarten Class of 1998-1999 (N=21,255), this study examined dual components of family income and material hardship along with parent mediators of stress, positive parenting, and investment as predictors of 6-year-old children's cognitive skills and social-emotional competence. Support was found for a model that identified unique parent-mediated paths from income to cognitive skills and from income and material hardship to social-emotional competence. The findings have implications for future study of family income and child development and for identification of promising targets for policy intervention. 相似文献
947.
Veenstra R Lindenberg S Zijlstra BJ De Winter AF Verhulst FC Ormel J 《Child development》2007,78(6):1843-1854
For this study, information on Who Bullies Who was collected from 54 school classes with 918 children (M age = 11) and 13,606 dyadic relations. Bullying and victimization were viewed separately from the point of view of the bully and the victim. The two perspectives were highly complementary. The probability of a bully-victim relationship was higher if the bully was more dominant than the victim, and if the victim was more vulnerable than the bully and more rejected by the class. In a bully-victim dyad, boys were more often the bullies. There was no finding of sex effect for victimization. Liking reduced and disliking increased the probability of a bully-victim relationship. 相似文献
948.
Vaughan Van Hecke A Mundy PC Acra CF Block JJ Delgado CE Parlade MV Meyer JA Neal AR Pomares YB 《Child development》2007,78(1):53-69
Infant joint attention has been observed to be related to social-emotional outcomes in at-risk children. To address whether this relation is also evident in typically developing children, 52 children were tested at 12, 15, 24, and 30 months to examine associations between infant joint attention and social outcomes. Twelve-month initiating and responding to joint attention were related to 30-month social competence and externalizing behavior, even when accounting for 15-month temperament ratings, 24-month cognition and language, and demographic variables. These results suggest that, in addition to associations with language and cognition, infant joint attention reflects robust aspects of development that are related to individual differences in the emergence of social and behavioral competence in childhood. 相似文献
949.
The longitudinal development of the intraindividual coupling between academic achievement, interest, and self-concept of ability (SCA) was analyzed in a sample of approximately 1,000 children between grades 1 and 12 (ages 6-17). Across all calculated indexes, the average level of coupling was positive. Individuals generally felt competent and interested in domains where they achieve well, and were interested in domains where they perceive their personal strengths. The degree of coupling was the highest between interest and SCA and the lowest between interest and achievement. For all indexes, evidence for an increase in coupling across time was found. Female gender was related to a lower level of coupling. There was evidence for a positive effect of conscientiousness on the amount of coupling. 相似文献
950.
ABSTRACT: This paper argues for an action-oriented conception of learning in higher education: one which marries higher order learning (coming to understand) with apprenticeship in knowledge work. It introduces epistemic tasks, forms and fluency as constructs that are useful in giving a more precise meaning to ideas about collaboration in knowledge construction. Discussion is seen as central to collaborative knowledge work and we examine the role of discussion in supporting weaker and stronger interpretations of collaborative knowledge construction. 相似文献