Natural hybridization of Japanese <Emphasis Type="Italic">Rhododendron</Emphasis> section <Emphasis Type="Italic">Brachycaryx</Emphasis> in Mount Kintoki in eastern Japan and concerns for genetic diversity in restoring their habitat

Native Rhododendrons section Brachycaryx in eastern Japan are decreasing in their natural habitats and the need to restore these habitats is increasing. Conservation of genetic diversity in restoring habitat requires clarification of the balance of interspecies genetic exchange which occurs in their natural habitats. In well-preserved natural habitats of Rhododendron dilatatum, R. kiyosumense, and R. wadanum and their natural hybrids R.×kuratanum and R.×hasegawai we investigated their geographical distribution, frequency, and flowering period. DNA analysis of the internal transcribed spacer (ITS) region was also conducted to confirm the species related to hybridization. Our findings in the field survey were: (1) Hybridizations occur in the overlap zones of related species. (2) R.×hasegawai occurs more frequently than R.×kuratanum, probably because the flowering seasons of R. kiyosumense and R. wadanum overlap longer than those of R. dilatatum and R. kiyosumense. (3) Natural hybrid occurrence is, nevertheless, under 9% of all related Rhododendrons section Brachycalyx. Analysis of the ITS region suggested that the two hybrids are generated from interspecific gene exchange, i.e., (4) R. dilatatum and R. kiyosumense relate to the formation of R.×kuratanum. (5) R.×hasegawai is a hybrid of R. wadanum and some species other than R. wadanum. On the basis of these findings we delineated several guidelines for restoring habitats of Rhododendrons of Section Brachycaryx with concerns for genetic diversity: (1) Before use, identify plant materials by morphological traits to determine whether they are original species or hybrids. (2) Investigate the distribution of remnant Rhododendrons section Brachycaryx before restoration. (3) Combine plant materials of original species in the natural distribution.     

Effect of Bt broccoli and resistant genotype of Plutella xylostella (Lepidoptera: Plutellidae) on life history and prey acceptance of the predator Coleomegilla maculata (Coleoptera: Coccinellidae)

The ecological implications on biological control of insecticidal transgenic plants, which produce crystal (Cry) proteins derived from the soil bacterium Bacillus thuringiensis (Bt), remains a contentious issue and affects risk assessment decisions. In this study, we used a unique system of resistant insects, Bt plants and a predator to critically evaluate this issue. The effects of broccoli type (normal or expressing Cry1Ac protein) and insect genotype (susceptible or Cry1Ac-resistant) of Plutella xylostella L. (Lepidoptera: Plutellidae) were examined for their effects on the life history of the predator, Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) over two generations. Additional behavioral studies were conducted on prey choice. C. maculata could not discriminate between Bt-resistant and susceptible genotypes of P. xylostella, nor between Bt and normal broccoli plants with resistant genotypes of P. xylostella feeding on them. The larval and pupal period, adult weight and fecundity of each female were not significantly different when C. maculata larvae fed on different genotypes (Bt-resistant or susceptible) of insect prey larvae reared on Bt or non-Bt broccoli plants. The life-history parameters of the subsequent generation of C. maculata fed on Bt broccoli-reared resistant P. xylostella were also not significantly different from those on non-Bt broccoli. These results indicated that Cry1Ac did not harm the life history or prey acceptance of an important predator after two generations of exposure. Plants expressing Cry1Ac are unlikely to affect this important predator in the field.     

NK细胞中过表达Livin的实验研究

目的:将携带Livin的质粒pIRES2-EGFP-Livin进行扩增,转染自然杀伤细胞(NK)及胃癌细胞株SGC-7901,并检测其在NK及胃癌细胞株SGC-7901中的表达。方法:将携带Livin基因的质粒p IRES2-EGFP-Livin进行扩增,鉴定质粒纯度与浓度;从健康人外周血中获得NK细胞,应用HP转染试剂将质粒pIRES2-EGFP-Livin转染体外培养的NK及胃癌细胞,对比分析NK及胃癌细胞株SGC-7901中基因转染效率及目的基因的表达情况。结果:用无血清培养基在体外成功的扩增大量的NK细胞;质粒提取试剂盒抽提得到大量无内毒素的质粒,质粒DNA基因序列并未发生突变,浓度和纯度较高。胃癌细胞株SGC-7901中观察到明显的质粒pIRES2-EGFP-Livin绿色荧光表达;而NK中未观察到绿色荧光表达。结论:质粒pIRES2-EGFP-Livin能使Lvin蛋白表达于胃癌细胞株SGC-7901中,而在NK中未表达。     

Evolution in Lego ®: A Physical Simulation of Adaptation by Natural Selection

We describe a physical simulation of natural selection in a population of legorgs, six-segment model organisms. Legorg morphology is genetically specified by five alleles on each segment. Legorgs show a simple form of motility that could evolve in originally sessile animals. This motility, the ability to move horizontally on a smooth surface, depends on the morphology and interaction of the six segments that produce different patterns of locomotion. Legorgs are selected for motility and reproduce in proportion to fitness. After just five generations, the average population motility increases 2.5 times. Additionally, we describe a slightly less time-consuming simulation of legorg evolution, where fitness is assigned by comparison with a template. The calculation of gene pools is precisely the same as in the previous simulation and produces very robust increases in fitness during five generations. The simulation is designed as a classroom experiment to explore the mechanism of natural selection. A test of its learning efficiency by evaluating the students’ conception of central aspects of evolutionary theory before and after showed a significant improvement. The surprising power of natural selection in this very simple physical system may also be exploited in more advanced experiments.     

The extracellular nuclease of Serratia marcescens: studies on the activity in vitro and effect on transforming DNA in a groundwater aquifer microcosm

A quantitative endonuclease assay, which relies on the introduction of single and double strand breaks into supercoiled plasmid DNA, was used to study the activity of the extracellular nuclease of Serratia marcescens SM6 in buffer and in groundwater. The parallel enzyme concentration-dependent production of relaxed and linear plasmid molecules suggests that the nuclease produces single and double strand breaks in duplex DNA. Bovine serum albumin stimulated the nuclease activity towards DNA and RNA and increased the stability of the enzyme against thermal inactivation. The DNase activity at 4 °C and 50 °C was almost half of that at the optimum temperature (37 °C). The nuclease was active in groundwater, although the specific activity was lower than in buffer. In a groundwater aquifer microcosm, mineral-adsorbed transforming DNA was substantially less accessible to the nuclease than was dissolved DNA. The data suggest that the extracellular nuclease of Serratia marcescens may contribute to DNA turnover in the environment and that adsorption of DNA to minerals provides protection against the nuclease.Abbreviations GW groundwater GWA groundwater aquifer     

Plasmid transfer to indigenous marine bacterial populations by natural transformation

Abstract Horizontal gene transfer among microbial populations has been assumed to occur in the environment, yet direct observations of this phenomenon are rare or limited to observations where the mechanism(s) could not be explicitly determined. Here we demonstrate the transfer of exogenous plasmid DNA to members of indigenous marine bacterial populations by natural transformation, the first report of this process for any natural microbial community. Ten percent of marine bacterial isolates examined were transformed by plasmid DNA while 14% were transformed by chromosomal DNA. Transformation of mixed marine microbial assemblages was observed in 5 of 14 experiments. In every case, acquisition of the plasmid by members of the indigenous flora was accompanied by modification (probably from genetic rearrangement or methylation) that altered its restriction enzyme digestion pattern. Estimation of transformation rates in estuarine environments based upon the distribution of competency and transformation frequencies in isolates and mixed populations ranged from 5 × 10⁻⁴ to 1.5 transformants/1 day. Extrapolation of these rates to ecosystem scales suggests that natural transformation may be an important mechanism for plasmid transfer among marine bacterial communities.     

Identification of target antigens of antiendothelial cell antibodies in healthy individuals: A proteomic approach

In order to identify target antigens of anti-endothelial cell (anti-EC) antibodies (AECA) in healthy individuals, we have used a proteomic approach combining 2-DE and immunoblotting. Whole cell protein extracts obtained from human umbilical vein EC (HUVEC) cultures were used as a source of antigens. Serum IgG from 12 healthy blood donors were tested at a concentration of 200 microg/mL. Targeted spots were identified by MS. The HUVEC proteome was composed of 884 protein spots. Among these, 61 +/- 25.8 (mean +/- SD) spots were recognized by serum IgG from healthy individuals, with marked differences from one individual to another. Among these spots, 11 were recognized by serum IgG from all healthy individuals tested. These spots corresponded to six different proteins with several spots corresponding to different isoforms of the same protein. Target antigens were: cytoskeletal proteins (beta-actin, alpha-tubulin, and vimentin); glycolytic enzymes (glucose-3-phosphate-deshydrogenase and alpha-enolase); and prolyl-4-hydroxylase beta subunit, a member of the disulfide isomerase family. This study shows that the repertoire of IgG AECA is heterogeneous among healthy individuals. IgG from all of the healthy individuals tested recognized a restricted set of highly conserved ubiquitous proteins playing key roles in cell biology and maintenance of homeostasis.     

Biological effects of some natural and chemical compounds on the potato tuber moth,Phthorimaea operculella Zell. (Lepidoptera:Gelechiidae)

The olfactory reaction of larvae and moths was investigated towards 18 oils (6 natural oils and 12 commercial chemical oils). Some of these oils such as peppermint and camphor (natural oils) and eugenol and camphene (commercial oils) were repellent to both larvae and moths. Other oils such as strawberry and d-limonene were attractive to both larvae and moths.Some of the repellent oils were, therefore, tested for their effect on certain biological aspects of the insects.Eugenol and peppermint oils, each at the 0.01% conc., caused a significant depression in the fecundity of moth and decreased the percentage of egg hatchability. Eugenol oil was much more effective than peppermint oil at 1%. Dried (leaves, fruits or seeds) powder of 14 different plants species were tested in different concentrations with talcum powder (carrier material) against egg deposition. The results indicated that dried powders of Allium cepa, Curcuma longa, Colocasia antiqurum, Ocimum basilicum. Dodonaea viscose and Thuja orientalis played a highly significant role in reducing egg deposition. The most impressive effect was displayed by powders of D. viscose and A. cepa, which caused the highest depression in egg deposition as well as in the emerging offsprings. Ethanolic extracts of 11 plants indicated that extracts of Pithuranthos tortosus and Iphiona scabra caused the maximum inhibition of egg hatchability, followed by C. longa, Citrullus colocynthia and T. orientalis. Ethanolic extracts of Schinus terebenthiflius (leaves) and I. scabra caused the highest depression in the deposited eggs, as they played a remarkable role as ovipositor deterrents.The majority of the plant extracts at 1% conc. could protect potato tubers at different intervals according to the calculated tuber damage index as follows: Iphiopna > Pithuranthos > Curcuma > Schinus (fruits) Thuja > Schinus (leaves) > Dodonaea > Citrullus.     

tRNA-dependent amide bond–forming enzymes in peptide natural product biosynthesis

In the ribosome-independent biosynthesis of peptide natural products, amino acid building blocks are generally activated in the form of phosphoesters, esters, or thioesters prior to amide bond formation. Following the recent discovery of bacterial enzymes that utilize an aminoacyl ester with a transfer ribonucleic acid (tRNA) in primary metabolism, the number of tRNA-dependent enzymes used in biosynthetic studies of peptide natural products has increased steadily. In this review, we summarize the rapidly growing knowledge base regarding two types of tRNA-dependent enzymes, which are structurally and functionally distinct. Initially, we focus on enzymes with the GCN5-related N-acetyltransferase fold and discuss the catalytic function and aminoacyl-tRNA recognition. Next, newly found peptide-amino acyl tRNA ligases and their ATP-dependent reactions are highlighted.