Analyzing somaclonal variation in micropropagated bananas (<Emphasis Type="Italic">Musa</Emphasis> spp.)

Summary In a micropropagation program, where it is of paramount importance to produce true-to-type planting material, somaclonal variation of any kind is undesirable. Variation among plants regenerated from tissue culture is termed ‘somaclonal variation’. In banana, somaclonal variants of different type have been reported with regard to plant morphology. This article discusses various factors due to which somaclonal variations may arise. Somaclonal variation may be detected by visual screening or by using molecular markers such as randomly amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), and by cytological studies. Although somaclonal variation is undesirable in the context of micropropagation, it can be used to advantage for genetic improvement of banana, as has been described.     

Purification,characterization and developmental expression of pig liver PSP

We have isolated a perchloric acid-soluble protein designated as PL-PSP from the post-mitochondria supernatant fraction of pig liver. It is soluble in 5% perchloric acid and purified by ammonium sulfate fractionation and CM-Sephadex chromatography. The PL-PSP showed approximately 80–90% homology with PSP isolated from rat liver (RL-PSP) with its partial amino acid sequences. The protein has a molecular mass of approximately 14 kDa which was slightly higher than that of RL-PSP. It inhibited protein synthesis in a rabbit reticulocyte lysate system. The expression of PL-PSP was predominant in liver, kidney and duodenum, and was also expressed in stomach, lung and brain. PL-PSP expression in liver increased from the 1st day to the 1st month. Thus, our findings are the first report on the presence of a PSP in porcine tissues which may be involved in the regulation of cellular growth and differentiation.     

Molecular cloning, expression, and purification of pig interleukin-5

 Interleukin-5 (IL-5) is thought to be a key cytokine in allergic inflammation. Pig IL-5 was cloned, sequenced, and expressed to enable us to study of the biological role of IL-5 in pigs used in a model for allergen-induced late-phase reactions. These pigs were sensitized to proteins extracted from Ascaris suum, resulting in hypersensitivity to this antigen in both the skin and airways, and a slight blood eosinophilia. Peripheral blood mononuclear cells from antigen-sensitized pigs were isolated and polyclonally stimulated. Total RNA was extracted and reverse transcribed into cDNA. IL-5 primers based on the cow IL-5 cDNA sequence were used to obtain an initial polymerase chain reaction product. 3′ rapid amplification of cDNA ends (3′RACE) and 5′RACE procedures were applied to identify the 3′ and 5′ ends, respectively. The full-length pig IL-5 cDNA is 405 base pairs long. Mature pig IL-5 was expressed in Escherichia coli with a His-tag for purification. The IL-5 protein is 115 amino acids long, has an estimated molecular weight of 14 000 M _r and forms a biologically active homodimer of 28 000 M _r . Pig IL-5 shows 65% amino acid identity to the human IL-5 sequence and 90, 88, 83, 62, and 61% identity to the cow, sheep, horse, mouse, and rat counterparts. Received: 29 June 1999 / Revised: 22 September 1999     

Genomic diversity among Vibrio cholerae O139 strains isolated in Bangladesh and India between 1992 and 1998

In order to assess the extent of genomic diversity among Vibrio cholerae O139 strains, restriction fragment length polymorphisms in two genetic loci, rrn and ctx, were studied. Analysis of 144 strains isolated from different regions of Bangladesh and India between 1992 and 1998 revealed the presence of at least six distinct ribotypes (B-I through B-VI) of which three were new ribotypes, and one of these was represented by a nontoxigenic O139 strain. Strains of ribotypes B-I through B-V shared 11 different CTX genotypes (A through K). Antimicrobial resistance patterns of the strains varied independently of their ribotypes and CTX genotypes. Results of this study suggest that V. cholerae O139 is undergoing rapid genetic changes leading to the origination of new variants, and temporal changes in antimicrobial resistance patterns may be contributing to the selection of different variants.     

棉铃虫抗药性基因频率的测定(英文)

本文介绍了用单个棉铃虫测定杀虫药剂抗性基因频率的灵敏方法。该技术是基于比较三个相等量单个棉铃虫的乙酰胆碱酯酶的活性,每个棉铃虫要用微量滴定板同时做3个试验（也可用Enppen－dorf管）（No．1－3）：1）不加抑制剂（No．1）;2）不加酶源（No．2）;3）加一定浓度的残杀威以抑制编码敏感AceS等位基因的乙酰胆碱酯酶,但不能抑制编码抗性AceR等位基因的乙酰胆碱酯酶。如果No．1和No．3的强度一样强,说明残杀威对乙酰胆碱酯酶的活性没有影响,那么基因型应是纯合抗性（AceRR,No3＝No．1）。No．2和地．3的强度一样弱时,说明残杀威完全抑制了乙酰碱酯酶的活性,那么基因型应是纯合敏感（AceSS,No．3＝No．2）。No．3的强度介于No．1（强）和No．2（弱）之间显示出残杀威部分地抑制了乙酰胆碱酯酶的活性;基因型是杂合型（AceSR,No．2＜No.3＜No．1）。作者用该方法测定了1995,1996两年从河北省邯郸和固安县棉田采集的棉铃虫,在邯郸棉铃虫抗药性高发地区,其抗性基因频率AceRR分别是68．3％和65．3％;但在棉铃虫抗药性低发区的固安县其抗性基因频率分别是23．9％和29．4％。     

β-Carotene inhibition of aflatoxin biosynthesis amongAspergillus flavus genotypes from Illinois corn

Thirty-nineAspergillus flavus genotypes (DNA fingerprinting) isolated from corn grown in a field near Kilbourne, Illinois were evaluated for their sensitivity to β-carotene (50 μg/ml) inhibition of aflatoxin B₁ biosynthesis. Inhibition of aflatoxin was greater than 90% for 28 of the genotypes and >70% for 38 of the 39 genotypes. FiveA. flavus strains (4 fingerprint groups) isolated from molded raw peanuts, NRRL 3239, NRRL 3357, NRRL 6514, NRRL 6515 and NRRL 13135, produced greater quantities of aflatoxin than all 39 genotypes isolated from corn, and were less sensitive to β-carotene inhibition.Aspergillus flavus NRRL 3357 is commonly used as inoculum in variety trials for aflatoxin resistance. Isolate identity and sensitivity to potential inhibitors in corn can be critical in assessing corn resistance to aflatoxin.     

Somatic embryogenesis in pearl millet (Pennisetum glaucum): Strategies to reduce genotype limitation and to maintain long-term totipotency

Three genotypes of Pearl millet were screened in vitro for induction of embryogenic callus, somatic embryogenesis and regeneration. Shoot apices excised from in vitro germinated seedlings or immature embryos isolated from green house established plants were used as primary explants. The frequency of embryogenic callus initiation was significantly higher in shoot apices in comparison with immature zygotic embryos. Moreover, differences between genotypes were minimal when using shoot apices. Friable embryogenic calli (type II) developed on the initial nodular calli after 1 to 3 months of culture. The frequency of type II callus is related to the composition of the maintenance medium and they were more often found in ageing cultures. The transfer of embryogenic calli onto auxin-free medium was sufficient for inducing somatic embryo development in short-term culture (3 months) while a progressive loss in regeneration potential was observed with increasing time of subcultures. Maturation of embryogenic calli on medium supplemented with activated charcoal, followed by germination of somatic embryos on medium supplemented with gibberellic acid, restored regeneration in long-term cultures. This revised version was published online in June 2006 with corrections to the Cover Date.     

鉴定猪,牛及绵羊肥大细胞的组织化学技术

研究证实Ｃａｒｎｏｙ液和中性缓冲福尔马林溶液（ＮＢＦ）是猪、牛及绵羊肥大细胞的优良的固定液,ＮＢＦ虽能很好地保存牛和绵羊的肥大细胞,但却阻断了猪的大多数肥大细胞、特别中肠粘膜肥大细胞（ＭＭＣ）及胸腺髓质肥大细胞（ＴＭＭＣ）对碱性染料的着染力。力苯胺蓝及阿尔辛蓝均为动物肥大细胞的优良染料,但阿尔辛蓝能使更多的肥大细胞着力。甲苯胺蓝及阿尔辛蓝均为动物肥大细胞的优良染料,但阿尔辛蓝能使理多的肥大细胞着染     

浙江地方猪种线粒体DNA多态及遗传多样性研究

本实验用ＡｐａＩ、ＡｖａＩ、ＢａｍＨⅠ、ＢｃｌⅠ、ＢｇｌⅠ、ＢｇｌⅡ、ＣｌａⅠ、ＤｒａⅠ、Ｅｃｏ ＲＩ、Ｅｃｏ ＲＶ、Ｈａｅ Ⅱ、Ｈｉｎｃ Ⅱ、ＨｉｎｄⅢ、ＨｐａⅠ、ＫｐｎⅠ、ＰｖｕⅠ、ＰｖｕⅡ、Ｓａｃ Ⅰ、ＳａｌⅠ、ＳｃａⅠ、ＳｍａⅠ、ＳｔｕⅠ、ＸｂａⅠ和ＸｈｏⅠ等２５种识别６个碱基对的限制性内切酶分析了浙江地方品种猪、浙江野猪等３０个个体的线粒体ＤＮＡ,共检出３０种限制性态型,可归结成３种单倍