Isolation of protoplasts from somatic embryos of carrot

Protoplasts were isolated enzymatically from synchronously induced globular somatic embryos from a carrot suspension culture. Among the macerating enzymes tested, Driselase was the most effective for release of protoplasts from embryos. A higher medium osmolarity was required for the isolation of protoplasts from embryos than from undifferentiated cells. Protoplasts from embryos were smaller than protoplasts from undifferentiated cells. On step gradients of Ficoll, protoplasts from embryos gave one major band. Protoplasts from undifferentiated cells gave two major bands, one lighter and the other heavier than the protoplasts from embryos.     

Development of plants from leaf discs of variegatedColeus and its relation to patterns of leaf chlorosis

Summary Leaf discs approximately 8 mm in diameter taken from green and from chlorotic areas of variegated leaves ofColeus were grown in light under sterile conditions in a mineral salt, sucrose, vitamin medium supplemented with auxin and cytokinin. Green shoots, which later formed roots, grew from both green and chlorotic discs in media containing suitable amounts of auxin and cytokinin. None developed in media supplemented with auxin alone or with cytokinin alone. Discs with young plants were transferred to soil. Plants that grew varied widely from those with no chlorosis to those with more chlorosis than the original variety from which the discs were taken. Plants grown from discs taken from green areas of leaves with chlorosis varied in patterns of chlorosis as much as those that grew from discs from chlorotic areas of leaves. This research was supported, in part, by The Conservation and Research Foundation.     

Comparison of chemical analyses of boat and helicopter-collected water samples

Helicopters can be used to collect water samples from many lakes over a wide geographic area within a relatively short time period. Here we report the results from an experiment in which sequential water samples from a lake were collected first from a nonmotorized boat and then immediately afterward from a helicopter. No significant differences were found between the means of the measurement of 20 chemical parameters for the two methods of collection. When compared to obtaining samples from a boat, collection of samples from a helicopter platform had no effect on the content of the water samples.     

Dispersal of Beauveria bassiana by the activity of nettle insects

Recent studies have shown that the entomopathogenic fungus Beauveria bassiana occurs naturally on the phylloplanes of several plants, including nettles. Insects could, by their activity, be contributing to this inoculum by dispersing it from other sites. The potential of nettle aphids Microlophium carnosum and their predator Anthocoris nemorum to disperse conidia of B. bassiana from soil to nettles and from sporulating cadavers in the nettle canopy was investigated in laboratory experiments. In petri dish assays, aphids showed potential to distribute B. bassiana from soil to nettle leaves. Predators dispersed inoculum from both soil and cadavers to nettle leaves in petri dishes. In microcosms, aphids did not disperse B. bassiana from the soil or from cadavers confined in the canopy, but A. nemorum were able to transfer inoculum from soil into the nettle canopy and to distribute conidia from cryptic cadavers. In some instances, infections were initiated in aphids and predators as a consequence of dispersal.     

兴安落叶松胚性愈伤组织诱导影响因子的研究

以成熟和未成熟合子胚为外植体,研究影响兴安落叶松（Larix gmelinii）胚性愈伤组织诱导的几种主要因子。结果表明兴安落叶松合子胚带胚乳培养有利于胚性愈伤组织的诱导;内蒙沙地种源成熟合子胚的诱导率显著（p<0.05）高于加格达奇山地种源;冷藏处理可以提高成熟合子胚胚性愈伤组织的诱导率;不同发育时期的未成熟合子胚的诱导率存在显著差别（p<0.05）,其中以子叶初期合子胚（7月5日）诱导率最高;2,4-D对胚性愈伤组织诱导的影响较大,且与BA、KT存在一定的协同作用;S培养基比DCR和MS培养基更有利于胚性愈伤组织的诱导;培养基中琼脂含量为4 g·L^-1时,诱导率较高。     

Influence of Indigenous Microbiota on Amount of Protein and Activities of Alkaline Phosphatase and Disaccharidases in Extracts of Intestinal Mucosa in Mice

The protein content and the activities of alkaline phosphatase, maltase, and sucrase were measured at 0800, 1000, 1200, 1400, and 1600 in saline extracts of the proximal small bowels of germfree and of ex-germfree mice colonized with an indigenous microbiota. In extracts prepared from germfree mice, the total activities of all of the enzymes were relatively constant throughout the sampling period. Likewise, the total activity of alkaline phosphatase in extracts prepared from associated mice varied little as a function of time. By contrast, the total activities of maltase and sucrase in the extracts from these latter animals varied significantly from sample to sample. The total activity levels in extracts from germfree mice were approximately twofold greater than the levels in extracts from associated mice. The specific activities of alkaline phosphatase and sucrase did not vary from sample to sample in extracts prepared from either type of mouse. In contrast, the specific activity of maltase in extracts prepared from both germfree and associated mice differed significantly from sample to sample. The specific activities of all three enzymes were greater in extracts from germfree animals than in those from associated animals. The protein content of extracts prepared from germfree mice also was greater than that of extracts prepared from associated animals at every sampling time. The amount of protein extractable from the mucosa of the small bowels of the former animals varied significantly at different sampling times during the day, whereas the amount of protein extractable from the tracts of associated animals remained relatively constant throughout the day. The indigenous microbiota apparently stabilizes in some way the amount of protein extractable from the mucosa of the mouse small bowel.     

Studies on the Somaclonal Variation of Regenerated Plants from Protoplasts of Actinidia deliciosa

Protoplasts were isolated from leaf, petiole and stem segment-derived calli induced from one pistillate plant of Actinidia deliciosa line No. 26. Regenerated plantlets were obtained from protoplasts of leaf-derived and stem segment-derived calli, while only calli regenerated from protoplasts of petiole-derived calli. Seventy-six plants from protoplasts of leaf-derived calli and 21 plants from that of stem segment-derived calli survived after transplanting or grafting during 1987–1989. One staminate plant and two pistillate plants bloomed in May, 1991 and fruited soon afterwards. In all of those three plants regenerated from protoplasts of leafderived calli, sex differentiation occurred from somatic cells of Actinidia was verified. Somaclonal variation on leaf shape and plant morphology was obviously appeared. Chromosome number identified from 16 plants varied from 116 to 180.     

Determination of the optimal tissue source and number of microsatellites for detection of zygotic origin of cattle twins

Abstract

Twenty pairs of cattle twins were genotyped for 3 to 12 microsatellites each using semen, blood, milk and hair roots. Chimaerism was recognized in 19 pairs by discrepancies in microsatellite analysis from milk and blood as opposed to semen and hair, or by detection of more than 2 alleles per genotype from milk and blood. Chimaerism of 2, 3 or 4 alleles was demonstrated in genotypes of twins from blood as compared to 1 or 2 alleles only from hair. The appearance of predominant bands in genotypes from blood or milk representing alleles of only one of the co‐twins was not consistent among the different microsatellites for the same twins. No evidence for germ cell chimaerism was found in semen of dizygotic male twins although our PCR system could detect cell mixes as small as a 1:100 ratio. Genotyping from either hair or semen for 4 microsatellites are sufficient to confirm zygotic origin of twins at .98 accuracy. Researchers should be aware of the possibility of erroneous genotyping when analyzing DNA from twins derived from blood or milk and the potential of chimaerism as an experimental model to study different immunological characteristics of cattle co‐twins.     

Generation of pluripotent stem cells from eggs of aging mice

Oocytes can reprogram genomes to form embryonic stem (ES) cells. Although ES cells largely escape senescence, oocytes themselves do senesce in the ovaries of most mammals. It remains to be determined whether ES cells can be established using eggs from old females, which exhibit reproductive senescence. We attempted to produce pluripotent stem cell lines from artificial activation of eggs (also called pES) from reproductive aged mice, to determine whether maternal aging affects pES cell production and pluripotency. We show that pES cell lines were generated with high efficiency from reproductive aged (old) mice, although parthenogenetic embryos from these mice produced fewer ES clones by initial two passages. Further, pES cell lines generated from old mice showed telomere length, expression of pluripotency molecular markers (Oct4, Nanog, SSEA1), alkaline phosphatase activity, teratoma formation and chimera production similar to young mice. Notably, DNA damage was reduced in pES cells from old mice compared to their progenitor parthenogenetic blastocysts, and did not differ from that of pES cells from young mice. Also, global gene expression differed only minimally between pES cells from young and old mice, in contrast to marked differences in gene expression in eggs from young and old mice. These data demonstrate that eggs from old mice can generate pluripotent stem cells, and suggest that the isolation and in vitro culture of ES cells must select cells with high levels of DNA and telomere integrity, and/or with capacity to repair DNA and telomeres.     

The origin of a new focus of infection with Echinococcus granulosus in Tasmania.

Hydatid cysts were discovered in cattle on King Island, north of Tasmania, where Echinococcus granulosus was thought to have been eradicated. Using enzyme electrophoresis, isolates from King Island were compared genetically with isolates from Tasmania and the mainland of Australia. The genetic distinctness of the King Island isolates make it unlikely that they originated from a recent introduction from either Tasmania or mainland Australia. Alternative possibilities, that the infection resulted from a recent introduction from another source or from previously undetected persistence of E. granulosus on King Island, could not be distinguished from available data.     

Study of the toxicological mechanism of acidified aerosols

More than 30 aerosol samples were collected from 1 place near Zaojiaban Road (downtown of Shanghai) and 1 village near Jiading country (suburb) by a stacked-filter air sampler. The coarse particulates (>2.5 μm) and the fine particulates (PM_2.5) and their unsoluble parts were analyzed by proton-induced X-ray emission. The cytotoxicity of particulates from the two places was evaluated by malondialdehyde (MDA) and thiazolyl blue (MTT) methods. The results show that the transition metal Fe, Cr, and Mn compounds from downtown are more easily soluble than those from the suburb, both in coarse and fine particulates, and the S content is much higher in particulates from downtown than that from the suburb. The cytotoxicity of the particulates from downtown is higher than that from the suburb and the cytotoxicity of acidified particulates is significantly higher than that of the controls. Because there are higher-soluble transition metal compounds that can induce free radicals in acidified particulates, the soluble transition metals may be one of the main factors for cytotoxicity.     

肺内调节肽对兔支气管上皮细胞分泌白介素的影响

为探讨肺内调节肽对气管上皮细胞（brochial epithelial cells,BECs）分泌功能的影响,实验观察了兔BECs在未受应激与臭氧应激两种条件下白细胞介素（interleukin,ILs）的分泌。结果发现：血管活性肠肽（vasoac-tive intestinal peptide,VIP）以未受应激BECs存在抑制作用,并使用臭氧应激BECs分泌ILs下降;表皮生长因子（epi-dermal growth factor,EGF）使未受应激BECs IL-1、IL-8分泌增加,使臭氧应激的BECs ILs分泌降低;内皮素-1（endothelin-1,ET-1）、降钙素基因相关肽(calctionin gene-related peptide,CGRP）可使未受应激的BECs分泌ILs增加,CGRP还可使臭氧应激的BECs ILs分泌增加。结果提示：肺内调节肽可调控BECs ILs的分泌,在调控气道炎症损伤信号传递方面具有一定的作用。     

Characterization of Escherichia coli strains isolated from urine of secretors and non-secretors

Abstract Strains of Escherichia coli isolated from urine of secretors (242) and non-secretors (121) were compared for their serotype and their ability to express mannose-sensitive (MS) haemagglutinins and mannose-resistant (MR) haemagglutinins and to produce haemolysin. The results of the survey refuted our hypothesis that strains with characteristics associated with virulence, those with MR haemagglutinins and/or haemolysins, would be isolated more frequently from non-secretors. MR haemagglutinins were detected among 36.4% of isolates from secretors and 27.3% of isolates from non-secretors. Haemolysin production was detected among 19.8% of isolates from secretors and 12.5% of isolates from non-secretors. Both MR haemagglutinins and haemolysin were detected only on 12.4% of strains from secretors and 6.7% of strains from non-secretors.     

不同生境下喜旱莲子草营养器官中抗氧化物质含量的比较

以水陆两种生境下生长的喜旱莲子草为实验材料 ,分别测定并比较了根、茎、叶可溶性蛋白及SOD、POD、Vc、GSH及绿原酸和类黄酮等抗氧化物质活性和含量 ,结果表明可溶性蛋白在叶中含量最高 ,并且水生环境中叶的含量高于陆生环境。除Vc外生态环境对各抗氧化物质含量影响具有一致性。水生环境下喜旱莲子草营养器官的抗氧化物质含量高于陆生环境下喜旱莲子草相应营养器官的含量。这是植物体内一种生理生化的生态适应     

Effect of ethanol on activity of the plasma-membrane ATPase in, and accumulation of glycine by, Saccharomyces cerevisiae

The pH optimum of the ATPase activity in plasma membranes from Saccharomyces cerevisiae NCYC 431 from 8 h cultures was around 6.5 and that in membranes from organisms from 16 h cultures near 6.0. The Km[ATP] of the enzyme was virtually unaffected by the age of the culture from which organisms were harvested, although the Vmax of the enzyme in membranes from organisms from 8 h cultures was higher than that for organisms from 16 h cultures. Ethanol non-competitively inhibited ATPase activity in membranes, although the inhibition constant for the enzyme from organisms from 8 h cultures was lower than that from organisms from 16 h cultures. Glycine accumulation by the general amino acid permease was non-competitively inhibited by ethanol. Inhibition constants were virtually the same for glycine uptake by deenergized organisms from 8 h and 16 h cultures, but under energized conditions the value was greater for organisms from 16 h rather than 8 h cultures. The data indicate that inhibition of plasma-membrane ATPase activity by ethanol could account, at least in part, for inhibition of glycine accumulation by ethanol.     

A microsatellite survey of cattle from a centre of origin: the Near East

Eight humpless cattle breeds from the Near East, three from Europe, one from West Africa and two zebu breeds from India were screened with 20 microsatellite loci. Breeds from the Near East revealed considerable levels of introgression from zebu cattle, which was apparent most in populations from the East and which declined in populations further West. This nonrandom pattern is suggestive of the introduction of zebu cattle from the East. Notwithstanding the overlay of zebu alleles, it was possible to demonstrate that Near Eastern cattle exhibited significantly higher levels of allelic diversity than breeds from other regions, which is consistent with the view that this region represents a primary domestication centre for Bos taurus cattle. The hypothesis that B. taurus and B. indicus cattle have separate domestic origins is also supported by the survey, a large genetic divergence being apparent between the nonhybrid taurine and zebu groups.     

Quinolone-resistant mutations of the gyrA gene of Escherichia coli

Summary DNA fragments of 8.5 kb containing the gyrA gene were cloned from Escherichia coli KL-16 and from four spontaneous gyrA mutants which showed various levels of resistance to quinolones. The gyrA gene was situated at about 4 kb in front of the nrdA gene and transcribed counterclockwise on the E. coli chromosome. It encoded a polypeptide of 875 amino acids with a molecular weight of about 97000. The four gyrA mutations were located strikingly close to one another within a small region near the N-terminus of the gyrA polypeptide, i.e., nucleotide changes from C to T, from C to G, from G to T and from G to T at nucleotides 248, 248, 318 and 199, respectively, resulting in amino acid changes from Ser to Leu, from Ser to Trp, from Gln to His and from Ala to Ser at amino acids 83, 83, 106 and 67, respectively. These mutations were situated in the relatively hydrophilic regions of the GyrA polypeptide and close to Tyr at amino acid 122 which has been shown to be the site covalently bound to DNA.     

Functional and structural relationship of various extradiol aromatic ring-cleavage dioxygenases of Pseudomonas origin

Abstract The extradiol ring-cleavage dioxygenases derived from seven different Pseudomonas strains were expressed in Escherichia coli and the substrate specificities were investigated for a variety of catecholic compounds. The substrate range of four 2,3-dihydroxybiphenyl dioxygenases from biphenyl-utilizing bacteria, 3-methylcatechol dioxygenase from toluene utilizing Pseudomonas putida F1, 1,2-dihydroxynaphthalene dioxygenase from a NAH7 plasmid, and catechol 2,3-dioxygenase from a TOL plasmid pWW0 were compared. Among the dioxygenases, that from Pseudomonas pseudoalcaligenes KF707 showed a very narrow substrate range. Contrary to this, the dioxygenase from pWW0 showed a relaxed substrate range. The seven extradiol dioxygenases from the various Pseudomonas strains are highly diversified in terms of substrate specificity.     

Use of in vitro cultures of Nicotiana benthamiana for the purification of grapevine virus A

Seedlings of Nicotiana benthamiana were inoculated with grapevine virus A (GVA). Three weeks later, upon systemic symptom expression, cultures were established in vitro using single nodes from these plants. GVA was purified from these cultures and from leaves of GVA-infected N. benthamiana plants maintained in the greenhouse. More virus was obtained from the proliferating in vitro node cultures than from the leaves. The use of in vitro cultures for virus purification represents a valuable practical application of plant tissue culture techniques.