Purification and Characterization of Lactobacillus bulgaricus Diaphorase

γ-Isomer of 1,2,3,4,5,6-hexachlorocyclohexane (BHC) showed greater decomposition on γ or UV irradiation of five isomers of BHC in crystalline state or in 2-propanol solution. The α- and δ-isomer of BHC and known la, 2a, 3e, 4e, 5e-pentachlorocyclohexane were separated from the irradiation product of crystalline γ-BHC. Four compounds were isolated from the irradiation product of γ-BHC in 2-propanol. Two compounds were tetrachloro-cyclohexenes (C₆H₆C1₄): γ-isomer (mp 86 ~87°C) and ?-isomer (mp 99 ~ 100°C). The other two were isomers of pentachlorocyclohexane (C₆H₇C1₅). One of them (mp 78 ~ 8.5°C) was consistent with known meso-1e,2a,3a,4a,5e isomer. The molecular structure of the other (mp 75°C) established by X-ray crystal structure analysis was 1α, 2α, 3α, 4β, 5α configuration or le 2a 3e 4e 5e conformation of CI atoms. A reaction mechanism was proposed that included a radical chain reaction and chlorine atom migration.     

The repellent effect of two pyrethroid insecticides on the honey bee*

ABSTRACT. . An improved model for the repellent effect of pyrethroid insecticides on insects was developed using small colonies of honey bees, Apis mellifera L., in flight cages. Conditioning to scented feeders allowed the separation of foraging bees from a single colony into paired treatment and control groups. The repellent response was characterized as a sublethal toxic effect resulting in transitory inhibition of activity. Permethrin and cypermethrin were shown to be contact repellents to honey bees; exposure was primarily to the tarsi and abdominal venter. Repellency was fully reversible within 24 h. No permanent effects on either memory function or foraging efficiency were observed following acute exposure.     

Oxygen transfer efficiency and environmental osmolarity response to neutralizing agents on l-lactic acid production efficiency by Lactobacillus paracasei

The effects of Ca(OH)₂, NH₄OH and NaOH as neutralizing agents on the efficiency of l-lactic acid production by Lactobacillus paracasei were investigated in this study. Fermentation performance with Ca(OH)₂ was superior to NH₄OH and NaOH because it had the highest oxygen transfer rate (OTR) and lowest environmental osmotic pressure. Much smaller bubbles were generated using a calcium lactate solution compared with those generated using ammonium lactate and sodium lactate solutions, indicating that Ca(OH)₂ had the highest OTR. Moreover, experiments demonstrated that ammonium lactate and sodium lactate caused more severe osmotic stress on cell growth than calcium lactate. In conclusion, the effects of neutralizing agents on l-lactic acid production efficiency could be ascribed to the contribution of lactates to OTR and environmental osmotic stress.     

胡芦巴水溶性甾体皂苷的提取分离工艺研究

以薯蓣皂苷元的提取率为指标,应用L9(3^4)正交试验设计优化了从脱多糖、脱脂胡芦巴豆粉中提取甾体皂苷的工艺条件,并且筛选了ZTC澄清剂对胡芦巴甾体皂苷水提取液的澄清条件。实验结果表明,影响水提取的主次因素为：提取次数＞提取温度＞固液比＞提取时间;最佳水提取条件为：固液比为1：10,在70℃下提取3次,每次120min得出胡芦巴种子水提取液的澄清条件如下：ZTCl 1澄清剂的加入次序是先加B组分再加入A组分;澄清剂B和A的最佳用量分别为1．0g/L和O．5g／L;加入组分A或B后在80℃下作用30min即可达到澄清目的。     

Saponins and Phenolics of Yucca schidigera Roezl: Chemistry and Bioactivity

Yucca schidigera (Agavaceae) is one of the major commercial source of steroidal saponins. Two products of yucca are available on the market. These include dried and finely powdered logs (yucca powder) or mechanically pressed and thermally condensed juice (yucca extract). These products possess the GRAS label which allows their use as foaming agent in soft drink (root beer), pharmaceutical, cosmetic, food, and feeding-stuffs industries. The main application of yucca products is in animal nutrition, in particular as a feed additive to reduce ammonia and fecal odors in animal excreta. The positive effects of dietary supplementation with yucca products on the growth rates, feed efficiency, and health of livestock seem to be due not only to the saponin constituents but also to other constituents. These observations prompted us to investigate the phenolic constituents of Y. schidigera. This study led to the isolation of resveratrol, trans-3,3′,5,5′-tetrahydroxy-4′-methoxystilbene, the sprirobiflavonoid larixinol along with novel phenolic derivatives with very unusual spirostructures, named yuccaols A–E and yuccaone A. Taking into account the multifunctional activities of resveratrol and the novelty of yuccaols A–E, structurally related to resveratrol, a program aimed to evaluate for yucca phenolics some of the activities exerted by resveratrol has been carried out. This review describes the chemistry of yucca saponins and phenolics, summarizes the biological activities of yucca products and constituents and gives an account on the actual and potential applications of yucca products.     

动物微生态制剂猪肠源乳球菌的分离与鉴定

试验的菌种是从宁夏平罗县边远农村基本自然生长的健康肉猪的小肠、大肠和盲肠中分离获得的,共分离出64株菌株。通过对这64株菌株的菌落形态观察和革兰氏染色镜检。筛选出9株进行了乳球菌属的生理生化鉴定,初步确定这9株属于乳球菌属(Lactococcus)。再通过糖醇类发酵产酸鉴定,确定2株为乳酸乳球菌乳酸亚种(L.lactissubsplactis),3株为植物乳球菌(L.plantarum),4株为棉籽糖乳球菌(L.raffi-nolactis)。各项鉴定结果均符合乳球菌属和相应种鉴定标准。     

Micropropagation of ‘Durondeau’ pear in modified-gelled medium

Summary The influence of partial substitution of agar by galactomannans (GMs) in culture media was studied in pear (Pyrus communis L. cv. ‘Durondeau’) micropropagation. GMs. extracted from seeds of Cassia fastuosa (cassia) or Cyamopsis tetragonolobus (guar gum, a commercial GM), were mixed in equal proportions with agar to a final concentration of 0.3% (w/v) for each type of gelling agent. The production of multiple shoots and the formation of roots from shoots were compared with the control solidified with agar alone at a concentration of 0.6% (w/v). In the media solidified with the mixtures of agar/guar and agar/cassia GMs, an, increase of 32 and 17%, respectively, was obtained in the number of regenerated shoots. The modified media promoted a higher number of roots and increased the rooting percentage. A maximum of 91% rooting was obtained in the medium solidified with the agar/cassia GM and containing 9.80 μM indole-3-butyric acid. Less callus formation at the base of the shoot was also observed on this medium. The improved in vitro performance of shoot formation and rooting, combined with a significantly lower cost, suggests a potential use of agar/GM gels in plant tissue culture.     

Stepwise identification of potent antimicrobial peptides from human genome

The increasing incidence of hospital acquired infections caused by antibiotic resistant pathogens has led to an increase in morbidity and mortality, finding alternative antibiotics unaffected by resistance mechanisms is fundamentally important for treating this problem. Naturally occurring proteins usually carry short peptide fragments that exhibit noticeable biological activity against a wide variety of microorganisms such as bacteria, fungi and protozoa. Traditional discovery of such antimicrobially active fragments (i.e. antimicrobial peptides, AMPs) from protein repertoire is either random or led by chance. Here, we report the use of a rational protocol that combines in silico prediction and in vitro assay to identify potential AMPs with high activity and low toxicity from the entire human genome. In the procedure, a three-step inference strategy is first proposed to perform genome-wide analysis to infer AMPs in a high-throughput manner. By employing this strategy we are able to screen more than one million peptide candidates generated from various human proteins, from which we identify four highly promising samples, and subsequently their antibacterial activity on five strains as well as cytotoxicity on human myoblasts are tested experimentally. As a consequence, two high-activity, low-toxicity peptides are discovered, which could be used as the structural basis to further develop new antibiotics. In addition, from 1491 known AMPs we also derive a quantitative measure called antibacterial propensity index (API) for 20 naturally occurring amino acids, which shows a significant allometric correlation with the theoretical minimal inhibitory concentration of putative peptides against Gram-positive and Gram-negative bacteria. This study may provide a proof-of-concept paradigm for the genome-wide discovery of novel antimicrobial peptides by using a combination of in silico and in vitro analyses.     

Clerocidin-mediated DNA footprinting discriminates among different G-quadruplex conformations and detects tetraplex folding in a duplex environment

Background

G-quadruplexes are polymorphic non-canonical nucleic acid conformations involved both in physiological and pathological processes. Given the high degree of folding heterogeneity and comparable conformational stabilities, different G-quadruplex forms can occur simultaneously, hence rendering the use of basic instrumental methods for structure determination, like X-ray diffraction or NMR, hardly useful. Footprinting techniques represent valuable and relatively rapid alternative to characterize DNA folding. The natural diterpenoid clerocidin is an alkylating agent that specifically reacts at single-stranded DNA regions, with different mechanisms depending on the exposed nucleotide.

Methods

Clerocidin was used to footprint G-quadruplex structures formed by telomeric and oncogene promoter sequences (c-myc, bcl-2, c-kit2), and by the thrombin binding aptamer.

Results

The easy modulability of CL reactivity towards DNA bases permitted to discriminate fully and partially protected sites, highlights stretched portions of the G-quadruplex conformation, and discriminate among topologies adopted by one sequence in different environmental conditions. Importantly, CL displayed the unique property to allow detection of G-quadruplex folding within a duplex context.

Conclusions

CL is a finely performing new tool to unveil G-quadruplex arrangements in DNA sequences under genomically relevant conditions.

General significance

Nucleic acid G-quadruplex structures are an emerging research field because of the recent indication of their involvement in a series of key biological functions, in particular in regulation of proliferation-associated gene expression. The use of clerocidin as footprinting agent to identify G-quadruplex structures under genomically relevant conditions may allow detection of new G-quadruplex-based regulatory regions.     

The antagonistic/synergistic effects of some medicinal plant essential oils,extracts and powders combined with Diatomaceous earth on red flour beetle,Tribolium castaneum Herbst (Coleoptera: Tenebrionidae)

Abstract

Red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is a prominent pest of stored products particularly cereal flour. Since resistance of this pest to common chemical insecticides is well documented, we were examined the synergistic/antagonistic interaction between Satureja hortensis L., Trachyspermum ammi L., Ziziphora tenuior L., Cuminum cyminum L. and Foeniculum vulgare Miller essential oils, ethanolic extracts and powders with Diatomaceous earth (DE) against T. castaneum adults under laboratory conditions at 27 ± 1 °C, 65 ± 5% RH and continuous darkness. We assayed repellency of ethanolic extracts and essential oils of mentioned plants on the pest. Results showed that DE had high toxicity to the pest. Plant essential oils and ethanolic extracts (except ziziphora) synergized the performance of DE. Nevertheless, plant powders elicited antagonistic effects (except ziziphora that exhibited synergistic effect). The most repellent EO and extract was cumin which exhibited mean repellency value on adult insect equivalent to 92.58 and 51.47%, respectively.