谈高中生物教学中如何培养学生的核心素养——以《染色体变异》一课为例

对高中生科学核心素养的培养已经成了21世纪教育的主要发展趋势。高中生物是一门能够充分激发学生学习兴趣的课程,如果在这门课程中加入一定的教学技巧,将能够保证学生的学习动机向正确积极的方向发展。高中生物大多数的概念都需要教师引导学生去理解和掌握。高中生物教师需要尽可能地在学习方案中加入一些生活实际的元素,帮助学生理解概念,完成教学目标,从而培养学生的核心素养。本文将就此展开综合论述,以《染色体变异》这一课为例,为教师培养学生生物核心素养提供自己合理的建议。

《染色体变异》重难点试析

《染色体变异》是普通高中人教版《生物》第五章第二节的教学内容。染色体变异包括染色体结构的变异和染色体数目的变异,其中染色体数目的变异是本节的教学重点,染色体组的概念和二倍体、多倍体和单倍体的概念及其联系又是难点。一些教师对此章节的处理往往犯难,主要对其中的重、难点内容的处置分寸难以把握。

基于概念图的移动学习探究——以生物课《染色体变异》为例

近年来，随着计算机技术、无线网络技术和移动通信技术的迅速发展，信息技术环境下的学习方式发生了重大变革，移动学习作为一种全新的学习模式悄然而生，并逐渐成为教育技术领域的研究热点，在世界范围内备受关注，许多国家纷纷启动不同研究内容的移动学习项目。与此同时，有关移动学习支持工具的研究也火热地进行，如资源开发工具、场景设计工具、建模工具、检索工具等，而本文旨在对概念图作为教学工具在移动学习中的应用进行尝试性研究。

基于多媒体的高中生物学互动课堂梅建——《染色体变异》互动课堂的构建

新课改为高中生物课堂的师生互动赋于了新的内涵，经过几年高中生物新课程教学的实践，觉得有效的课堂互动，既能突出教学的重点和难点，又有助于学生创造思维的形成。下面就《染色体变异》互动课堂几点设计：

Effect of Two Herbicides on the Growth of Early Seedlings of Rye(Secale cereale)

[Objective]The aim was to study the effect of herbicide on the growth of early seedlings of rye（Secale cereale）.[Method]Effect of two kinds of herbicide（Atrazine and APM）on seedling growth of rye was investigated at the physiological,biochemical and cellular level.[Result]The Atrazin significantly decreased the contents of chlorophyll a,b and soluble proteins.Rye seeds were treated with 0.01-1 mg/L Atrazine for 16 h,the contents of chlorophyll a and b decreased from 1.26（a）,0.49（b）mg/g FW（control）to 1.15（a）,0.46（b）mg/g FW（0.1 mg/L）and 0.81（a）,0.33（b）mg/g FW（1.0 mg/L）.The content of soluble protein decreased with the increasing concentration of Atrazin.Atrazin had no significant influence on the cell division and chromosome structure variation.The contents of chlorophyll a,b and soluble proteins had no significantly change under the treatment of APM,but the number of chromosome structure variation such as chromosome bridge,multipolar division cells,lagging chromosome and unequal division cells increased significantly.[Conclusion]The critical concentration of Atrazine was 0.1-1.0 mg/L and 4 mg/L of APM in rye.

Fine mapping and marker-assisted selection (MAS) of a low glutelin content gene in rice

Rice with low glutelin content is suitable as functional food for patients affected with diabetes and kidney failure. The fine mapping of the gene(s) responsible for low glutelin content will provide information regarding the distribution of glutelin related genes in rice genome and will generate markers for the selection of low glutelin rice varieties. Following an SDS-PAGE screen of rice germplasm from Taihu Valley of China, Japonica selection W3660 is identified to be a novel mutant characterized with low glutelin content. For fine mapping the mutant gene for low glutelin content, F2 and F3 populations were derived from a cross between W3660 and Jingrennuo. SDS-PAGE analysis of the total endosperm protein showed that the low glutelin content trait was controlled by a single dominant nuclear gene. Genetic mapping, using SSRs, located this gene to chromosome 2, in the region between SSR2-001/SSR2-004 and RM1358. The dis- tances of the two markers to the target gene were 1.1 cM and 3.8 cM respectively. By semi-quantitative RT-PCR analysis, the transcripts of GluB4/GluB5 genes located within the region do not change. However, GluB5 gene located proximal to SSR2-001/SSR2-004 was specifically reduced. SSR profiles of seven Japonica varieties were compared with that of W3660 for loci in the relevant genetic region. The markers SSR2-004 and RM1358 were used for marker- assisted selection. The selection efficiencies of SSR2-004 and RM1358 were 96.8% and 92.7% respectively. This provides a standard starting point for the breeding of low glutelin content rice varieties in China.

Morphological and karyotypic variation in three wild populations of Meretrix meretrix

Three wild populations of Meretrix meretrix sampled from Dongxing, Beihai, and Shankou along the coast of Guangxi, China, were investigated with morphometry and karyometry. Six morphological indices (shell length, shell height, shell width, hinge length, total wet weight and shell weight) were measured. Differences in all morphological indices except hinge length were significant among the three populations (P < 0.05). The mean values of these indices (except for the hinge length) in the Dongxing population were larger than those in the Beihai and Shankou populations, although the latter had the largest hinge length. The karyotype of the Beihai, Shankou and Dongxing samples had ten metacentric, six submetacentric, and three subtelocentric chromosome pairs. No significant difference was shown in the centromeric index values of the chromosomes in the populations (P>0.05). However, the order of metacentric, submetacentric and subtelocentric chromosome pairs was variable among the three populations. The results indicate a high level of inter-population variation in morphology and karyotype.

Germline MLH1 and MSH2 mutational spectrum including frequent large genomic aberrations in Hungarian hereditary non-polyposis colorectal cancer families:Implications for genetic testing

AIM: To analyze the prevalence of germline MLH1 and MSH2 gene mutations and evaluate the clinical characteristics of Hungarian hereditary non-polyposis colorectal cancer (HNPCC) families. METHODS: Thirty-six kindreds were tested for mutations using conformation sensitive gel electrophoreses, direct sequencing and also screening for genomic rearrangements applying multiplex ligation-dependent probe amplifi cation (MLPA). RESULTS: Eighteen germline mutations (50%) were identifi ed, 9 in MLH1 and 9 in MSH2. Sixteen of these sequence alterations were considered pathogenic, the remaining two were non-conservative missense alterations occurring at highly conserved functional motifs. The majority of the defi nite pathogenic mutations (81%, 13/16) were found in families fulfilling the stringent Amsterdam Ⅰ/Ⅱ criteria, including three rearrangements revealed by MLPA (two in MSH2 and one in MLH1). However, in three out of sixteen HNPCC-suspected families (19%), a disease-causing alteration could be revealed. Furthermore, nine mutations described here are novel, and none of the sequence changes were found in more than one family.CONCLUSION: Our study describes for the f irst time the prevalence and spectrum of germline mismatch repair gene mutations in Hungarian HNPCC and suspected-HNPCC families. The results presented here suggest that clinical selection criteria should be relaxed and detection of genomic rearrangements should be included in genetic screening in this population.

Structural Variation Analysis of Mutated Nannochloropsis oceanica Caused by Zeocin Through Genome Re-Sequencing

Zeocin can cause double strand breaks of DNA and thus may be employed as a mutagen. In this study, two strains of Nannochloropsis oceanica, the wild and the Zeocin-tolerant strains, were re-sequenced to verify such function of Zeocin, The results showed that Zeocin can mutate the N. oceanica genome and cause the structural variation. Zeocin either swept away or selected the alleles of genes functioning in ubiquitin-mediated proteolysis, alpha-linolenic acid metabolism, ascorbate and aldarate metabolism, ribosome biogenesis, and circadian rhythm, indicating that N. oceanica may have adjusted its metabolic performances for protein, carbohydrate, and lipid, and changed its ribosome biosynthesis and living rhythm to survive in Zeocin containing medium. In addition, Zeocin caused mutation may have influenced the expression of a set of tanscription factors. It was concluded that Zeocin effectively caused the structural variation of the genome of N. oceanica, and forced the microalgae to select out the alleles of a set of genes around these variations in order to adapt to Zeocin containing medium. Further studies on the genetic basis of the phenotypic adaptation of this haploid and asexual microalga and the application of Zeocin to its genetic improvement are very important.

Pollen-embryogenesis and chromosomal variability in anther culture of Brassica hirta Moench (Sinapis alba L)

The anther cultures of Brassica hirta underwent pollenembryogenesis and callusing,which showed a wide range of chromosome numbers varying from 9 (n=12) to a highly polyploid.For embryogenesis,pretreatment of floral buds in 0.4 M sucrose solution for 72 hrs at 4℃ was superior to freshly cultured anthers.Culture temperature of 30℃ for 14 days before maintenance of cultures at 25℃ was significantly beneficial for embryo yield in comparison to cultures continuously incubated at 25℃.Dark treatment during culture was more effective for pollen-embryo yield.

Variation in chromosome number in the seedling progeny of a somaclone of Paspalum dilatatum

The somaclone, C39, derived by tissue culture from the obligate apomict Paspalum dilatatum cv Raki (2n=50), had 50 chromosomes and a karyotype apparently identical to Raki.SC2 seedlings of C39 showed a high degree of phenotypic variation which was of ten associated with increased chromosome numbers, but some of the variant seedlings were karyotypically indistinguishable from Raki or C39. Plants with increased chromosome numbers exhibited a high degree of intraplant chromosome variation (aneusomaty). In one of the SC2seedlings, the chromosome number of root tip cells varied from 58 to 82 and in several other seedlings the range was more than 10. The results suggested that the ability to form seed apomictically was much reduced in C39 and that this plant showed some capacity for sexual reproduction and the resulting seedlings, with a chromosome number of about 70, were genetically unstable. Of 11 SC2 seedlings examined cytolog ically, 6 did not produce any viable seed. Seedlings grown from seed of the remaining 5 plants showed that aneusomaty persisted in the SC3 generation. SC3 seedlings which were phenotypically similar to their maternal parent showed a similar range of chromosome numbers to that parent. Some of the SC3 seedlings exhibited an even wider range of chromosome numbers (e.g.56-136), and these plants were all dwarfs.

Cytogenetic Diagnosis and Analysis of the Clinical Profile of Individuals with Non-down Syndrome Intellectual Disability

Chromosomal alterations are the main causes of genetic diseases. One of the characteristics of certain genetic syndromes is ID （intellectual disability） presented by the individual in varying degrees. The study of the ID, its etiology, association or not with chromosomal abnormalities and a clinical diagnosis associated with the examination of karyotype are important aspects to consider when providing genetic counseling for families. Due to the lack of similar studies and of easy access to cytogenetic services for the Amazonian population, this study aimed to contribute to the advancement of this line of study in the state, analyzing the karyotype of individuals with ID, not Down Syndrome treated at the APAE-Manaus and identifying the main types of chromosomal alterations in the individuals analyzed. Analyzes were performed of the clinical diagnosis through investigation of the data from the interview and medical records as well as analysis of the karyotype of 31 patients with non-Down syndrome ID, attended in the APAE-Manaus. Of these subjects, 20 were female and 11 male. The results showed only 2 cases of chromosome abnormalities are detectable by classical cytogenetics, one of mosaic Turner syndrome and one a heterochromatic variant. It is therefore necessary to complement the study with the addition of molecular techniques for the investigation of microdeletions and/or other alterations not detectable through the banding technique, mainly for individuals whose dysmorphisms indicate a suspected syndrome.

Histone Variant H3.3:A versatile H3 variant in health and in disease

Histones are the main protein components of eukaryotic chromatin. Histone variants and histone modifications modulate chromatin structure, ensuring the precise operation of cellular processes associated with genomic DNA. H3.3, an ancient and conserved H3 variant, differs from its canonical H3 counterpart by only five amino acids, yet it plays essential and specific roles in gene transcription, DNA repair and in maintaining genome integrity. Here, we review the most recent insights into the functions of histone H3.3, and the involvement of its mutant forms in human diseases.