维生素A水平对獭兔生产性能及血液生化指标的影响

选用45日龄Vc-Ⅱ新品系獭兔54只,研究维生素A水平对獭兔生产性能及血液生化指标的影响。结果表明,在基础日粮中添加10000IU/kg维生素A可显著提高獭兔的日增重(P<0.05)、降低料肉比(P>0.05)、降低血清BUN含量(P<0.01)。建议VC-Ⅱ生长獭兔日粮中维生素A的添加量为10000IU/kg。     

Aspects of the distribution and growth of bluemouth (Helicolenus dactylopterus, Delaroche 1809) since its invasion of the northern North Sea in 1991

Recent trends in the abundance, distribution and growth of bluemouth in Scottish waters are described. The observations are all based on an ecologically important time‐series database of trawl surveys conducted annually between 1925 and 2004 by Fisheries Research Services, Aberdeen. We examine the period 1985–2004 in detail. Bluemouth abundance has increased over the last decade both along the continental shelf west of Scotland and in the North Sea. In 1991 bluemouth appeared in the northern North Sea as a distinct cohort, with total lengths ranging between 6 and 8 cm. 1991 was a year of exceptional Atlantic inflow into the North Sea, and it is likely that the bluemouth used this water mass as a highway, entering from the north and west as small individuals. The fish from 1991 grew steadily and formed a distinct length mode that we track here until its disappearance in 2002. In the first few years following this influx, bluemouth were recorded all around the northern North Sea, but since 1997 numbers have declined and its distribution has shrunk into one of two International Council for the Exploration of the Sea (ICES) statistical rectangles (39F1 and 40F2) which are positioned in the central part of the North Sea. Since 1991 only one subsequent and relatively minor immigration of bluemouth into the North Sea has taken place, in 1998. The composition of the North Sea bluemouth population as a single cohort allows its spatial distribution, expansion and growth rate to be charted, discussed and described.     

Consequences of less intensive farming on the landscape: an example of vegetation dominance by Chaerophyllum aureum in the meadows of a Pyrenean valley in France

The impact of agricultural practices on the dynamics of weed invasion in a rural landscape was studied by describing the spatial distribution of Chaerophyllum aureum populations colonising less intensive managed hay meadows. Polyphenol compounds were used as individual markers to identify the structure of C. aureum diversity, in terms of its scale and patterns, within and between fields along the bottom of a Pyrenean valley. The results revealed, firstly, the existence of a dominant `genotype' successfully colonising the entire area, and secondly, the maintenance of high levels of polyphenol diversity within five different populations. This spatial arrangement of `genetic' population diversity was obviously not related to the natural reproduction and dispersal patterns of this species, but to human practices of hay production, the principal effect of which is to mix seeds of different genetic origin and thus accelerate and amplify the colonisation process of adapted `genotypes'.     

水稻胚性悬浮细胞系建立过程中的生理生化变化

本文详细分析了水稻广亲和中粳品系０２４２８胚性悬浮细胞系建立过程中的培养液渗透值、ＰＨ值，呼吸作用，过氧化物酶同工酶，碳、氢及矿质元素的变化。结果如下：１、前期、中期和后期悬浮细胞系（好胚性悬浮细胞系）的培养液渗透值在一次继代培养的０－３天期和后期悬浮细胞比前期悬浮细胞更多地利用氨基酸作为代谢底物。后期悬浮细胞的ＥＭＰ途径相对稍低，而ＨＭＰ、ＴＣＡＣ途径较前期、中期稍强。３、从前期－中期－后期，过     

Analysis of genomic variability in transgenic sugarcane plants produced by Agrobacterium tumefaciens infection

Three transgenic sugarcane populations produced by Agrobacterium tumefaciens infection were analysed for the presence of genomic variability. Plants of the original cultivar, plants regenerated without transformation, as well as transformed and untransformed calli were used as control treatments. Amplified fragment length polymorphism (AFLP) of DNA extracted from leaves or calli assessed genomic profiling. The average DNA polymorphism within each population was determined by calculating the polymorphism index, while the extent of genomic dissimilarity among individual plants within transgenic populations was verified in unweighted pair group method using arithmetic averages dendrograms. The results showed that the production of transgenic sugarcane plants by A. tumefaciens infection is accompanied by limited but detectable genomic changes and that, on average, these occur at the same rate in plant populations carrying different transgenes. Main factors contributing to somaclonal variation in transgenic sugarcane plants have been verified by pre-existing DNA polymorphism into the donor genotype and in vitro culture steps during the transformation procedure. The relevant practical conclusion from this finding is that the AFLP analysis may be effectively used to identify individual transgenic plants with the least genomic deviation from the parental ones. The selected genotype would be conserved as cultivated sugarcane is asexually propagated.     

玉米杂交种及其亲本自交系的生化指纹鉴定

本试验以浙单9号等五个玉米杂交组合及其亲本自交系为材料,进行种子盐溶蛋白聚丙烯酰胺凝胶电泳等多种电泳鉴定方法的研究,以揭示玉米杂交种及其亲本自交系的“生化指纹”(biochenucal fingerprint),以及筛选出适合于玉米杂交种及其亲本自交系真实性和纯度鉴定的方法。结果表明,各供试玉米杂交种及其亲本自交系都具有相应的、唯一的种子盐溶蛋白聚丙烯酰胺凝胶电泳所显现的生化指纹。对于有些组合。玉米芽鞘和叶片绿色组织过氧化物酶同工酶电泳图谱存在阴极第4、第5酶带差异,因这两条酶带的差异稳定,并且重现性好,故能用过氧化物酶同工酶技术对其进行有效地鉴定。上述两种方法,尤其是前者,因技术要求不高,费用低,快速及重现性好等特点,能满足我国目前种子检验室日常玉米品种纯度快速测定工作的要求,具育良好的应用前景。     

Chemical and flavour changes in jackfruit (Artocarpus heterophyllus Lam.) cultivar J3 during ripening

Chemical composition (titratable acidity, moisture content, crude fibre, colour, pH, soluble solids, sugars, organic acids) and flavour changes during ripening of jackfruit (Artocarpus heterophyllus L.) cultivar J3 were evaluated. Significant (p < 0.05) changes in titratable acidity and colour was obtained, but no significant changes were found in moisture and crude fiber contents during ripening. Total soluble solids and total sugars increased significantly (p < 0.05) throughout the ripening process. Total soluble solids at the top portion of the fruit were significantly (p < 0.05) higher than middle and bottom portions of the same fruit. A high content of malic acid was found in unripe fruit (day 1). In contrast, ripened fruit (days 5 and 6) contained a high amount of citric acid. Overall, the total amount of organic acids was found to decrease from the early to later stage of ripening. A total of 23 volatile compounds were tentatively identified by GC and GC–MS. The number of peaks was observed to increase throughout the ripening process. In this study, data obtained suggest that the ripening process of jackfruit was at its optimum at day 5 after harvest.     

Graft-transformation,the mechanism for graft-induced genetic changes in higher plants

Summary In our previous report of a series of experiments involving ordinary grafting, virus-inoculated grafting and DNA treatment in Capsicum annuum L., we described the variants as well as gene analyses of individual variants, together with the characteristics of the graft-induced genetic changes obtained.Microhistological analysis of the stock stems revealed that chromatin masses, stained to greenish blue and in various sizes and shapes, were moving through cell wall and intercellular space from the lignifying and dying cells, stained to lighter purplish brown, towards the vascular bundles (Fig. 1). I discussed the mechanisms of chromatin transfer from the stock dying cells through the vascular system across the graft-union to the growing point(s) of the scion (Fig. 3), and how that process causes transformation in the fast dividing scion flower primordia (Fig. 4).The significance of chromatin translocation can be understood in the following way: Genetic information is never transmitted from the stock to the scion, unless a DNA molecule larger than a functional unit such as a gene translocates from the stock, and unless the DNA molecules per se are integrated into new cell nuclei of the scion. In other words, no transmission of genetic information will take place, if DNA molecules of the stock disintegrated to nucleotides, as when a protein molecule is digested into amino acids, and are utilized by the scion simply as raw material in the formation of new cell nuclei with its own DNA strand as template.Also discussed were the significance of mentor methods, and the importance of distinguishing between horticultural graft and genetical graft (Fig. 2).     

Colchicine-induced heritable variation in cell size and chloroplast number in the leaf cells of inbred ryegrasses (Lolium perenne,L. multiflorum)

Summary A 3 hr period of treatment with a 0.2% aqueous solution of colchicine was given to one week old seedlings of 3 inbred lines of perennial ryegrass (Lolium perenne) and 4 lines of Italian ryegrass (L. multiflorum). The surviving plants developed as mixoploids and were self-pollinated. In the following generation (CT1) the seeds were grown without further treatment, and were screened cytologically at the seedling stage to separate out diploids from tetraploids. Only the diploids were kept, and in this CT1 generation comparisons were then made between controls (2x) and colchicine-treated diploids (C2x) for leaf mesophyll cell size and chloroplast number variation. Heritable differences were found such that the cell plan areas and/or the numbers of chloroplasts per cell were significantly greater in the C2x compared with the 2x treatment in 3 and 5 out of the 7 lines. In each case there was enhancement of chloroplast numbers independently of the variation in cell size.     

黄淮平原冬小麦分蘖成穗动态与气候生态条件关系的研究

河南省黄淮平原冬小麦分蘖消长的一般规律是:“两个盛期,一个高峰,越冬不停,集中死亡”.用白天平均温度积温(∑Tid)作生物学时间,代替自然天文时间,通过对本区冬小麦分蘖动态与气候生态关系的研究,黄淮平原冬小麦分蘖成穗随气温、土壤湿度等气候生态环境而变化的规律是:(1)最高群体以前:f=y_m/(1+e~(a-b∑Tid)·f_s·f_a-f_m (∑Tid相似文献