枯草芽孢杆菌B2菌株产生的抑菌活性物质分析

枯草芽孢杆菌B2菌株产生的胞外物质经盐酸沉淀，甲醇抽提获得粗制备物。利用HPLC系统将粗制备物过Xterra RPl8层析柱分离，共获得120管收集液。以抑制小麦赤霉病菌分生孢子萌发为指标对各管收集液的抑菌活性进行了测定。通过LC-MS分析，结果表明B2菌株胞外存在3种抑菌物质，即脂肽类抗生素表面活性素、多烯类和一种分子量为564的结构未知的新物质。     

In growing pigs,nutritive value and nutrient digestibility of distillers’ by-products obtained from two varieties of rice

In South-East Asia, rice distillers’ by-product (RDP) is a widely abundant feedstuff whose adequate incorporation into pig diets is still questionable. Especially, effects of RDP on nutrient digestibility of growing pigs fed corn-soybean meal-based diet are lacking. The objective of this study was to determine nutrient digestibility and energy value of ordinary (ORDP) and glutinous (GRDP) rice distillers’ by-product in growing pigs. Two groups of 12 castrated crossbred barrows (Duroc × Landrace × Yorkshire), about 3 months old, 38?±?1.04-kg initial body weight, were each allocated to a 15-day experiment in which pigs were divided into three isonitrogenous diet-groups. The animals were housed individually in metabolism cages for separated collection of feces and urine. Each diet-group was provided either a control corn-soybean meal diet or a diet in which corn and soybean meal were partly replaced by ORDP or GRDP at 15 or 30% on diet dry matter basis. Glutinous by-product especially showed higher levels in crude protein, neutral/acid detergent fiber, total branched-chain amino acids, and butyric acid. When compared to the control diet, ORDP tented to increase DM intake (P?= 0.054) but decreased energy (P?< 0.001) and crude protein (P?< 0.04) digestibility, while GRDP decreased DM intake (P?< 0.001). Both GRDP and ORDP products negatively affected digestibility of ether extract. The average digestible and metabolizable energy of ORDP and GRDP were 17.0 and 16.6, and 17.7, and 17.1 MJ/kg DM, respectively. In conclusion, these results show that both RDP, and especially GRDP, are highly valuable protein and energy sources for pig production.

     

Wild crop relative populations hot-spots of diversity are hot-spots of introgression in the case of pearl millet

Wild crop relatives are unique genetic resources for crop adaptation. Increasing pressure from agriculture threatens these populations both by reducing their habitats and by creating opportunities for wild-cultivated hybridization. In this study, we assessed the diversity of 38 wild pearl millet populations covering the whole known distribution of the species in Africa, which extends from Senegal to Sudan. Using genetic analyses of 10 cultivated varieties as control, we demonstrate the high diversity harbored by these wild populations. Diversity patterns suggest a diversity hot-spot in the southern part of the wild population’s range. However, this high wild genetic diversity could partly be explained by introgression from cultivated varieties. Such introgression is widespread in the Sahel. We validate the impact of cultivated introgression on the diversity of the wild population using a genetic introgression model. The introgression distorts the real assessment of the diversity of the wild population, and the burden of this gene flow compromises the long term survival of the wild populations’ original genome. Our study also questions the long term survival of the crop’s wild relatives.     

Reliable detection of unevenly distributed Verticillium dahliae in diseased olive trees

Verticillium wilt caused by Verticillium dahliae is one of the most threatening diseases of olive worldwide. For pre‐planting and post‐planting control of verticillium wilt in olive trees, availability of a rapid, reliable and non‐destructive method for detection of V. dahliae is essential. For such a method, suitable and easily performed sampling and efficient processing of samples for extraction of DNA are necessary. In this study, the suitability of young twig and leaf samples of olive trees, which are easy to collect and extract DNA from, were assessed for the detection of V. dahliae in routine procedures. The lower (about 50 cm from the tip) and top parts (about 5 cm from the tip) of twigs, as well as leaves from infected olive trees were screened for V. dahliae infection and distribution using real‐time PCR. The biomass of V. dahliae detected in individual twigs was highly variable, but there was no significant difference between mean quantities of V. dahliae DNA detected in top and lower parts of twigs. Furthermore, it was demonstrated that analysis of combined samples containing DNA extracted from five twigs of an infected tree accurately detected the presence of the pathogen. Similarly, testing combined samples of 5–10 leaves enabled reliable detection of the pathogen in an infected tree. The development of this assay enables reliable detection of V. dahliae in infected olive trees that can aid in management decisions for the implementation of integrated disease management.     

<Emphasis Type="Italic">Fibulorhizoctonia psychrophila</Emphasis> is the causal agent of lenticel spot on apple and pear fruit in the Netherlands

In a survey for postharvest diseases of apples and pears in the Netherlands, an unknown postharvest fruit rot was observed. The disease appeared to originate from infected lenticels. A fungus was consistently isolated from the decayed fruits. The fungal pathogen was isolated on potato dextrose agar, and at low temperatures development of a fast-growing whitish mycelium was observed. Growth of this fungus was observed between 1 and 20 °C with an optimum at 15 °C, while incubation of mycelium at 25 °C resulted in no growth. The isolates did not produce asexual or sexual spores. The isolates were characterized and identified by morphology and molecular phylogenetic analysis. Genomic DNA was isolated and amplified using ITS1-ITS4, EF1 and RPB2 primers, and BLAST searches in GenBank placed the fungus taxonomically in the genus Fibulorhizoctonia, with the highest matches to F. psychrophila. Pathogenicity of representative isolates from apple and pear fruit was confirmed under laboratory conditions. To the best of our knowledge this is the first report of F. psychrophila causing lenticel spot on apple and pear, and also the cause of a whitish mould on storage bins.     

Responses of rainbow trout intestinal epithelial cells to different kinds of nutritional deprivation

In order to develop an in vitro system to study the cell biology of starvation in the fish intestine, rainbow trout intestinal epithelial cells were subjected to three kinds of nutrient deprivation and evaluated for 7 days. The RTgutGC cell line was grown into monolayers in Leibovitz’s basal medium supplemented with fetal bovine serum (L15/FBS) and then subjected to deprivation of serum (L15); of serum, amino acids, and vitamin (L15/ex); and of all nutrients (L15/salts). After 7 days of nutrient deprivation, the cells remained attached to the plastic surface as monolayers but changes were seen in shape, with the cells becoming more polygonal, actin and α-tubulin cytoskeleton organization, and in tight junction protein-1 (ZO-1) localization. Two barrier functions, transepithelial electrical resistance (TEER) and Lucifer Yellow (LY) retention, were impaired by nutrient deprivation. In L15/FBS, cells rapidly healed a gap or wound in the monolayer. In L15 and L15/ex, some cells moved into the gap, but after 7 days, the wound remained unhealed, whereas in L15/salts, cells did not even migrate into the gap. Upon nutrient replenishment (L15/FBS) after 7 days in L15, L15/ex, or L15/salts, cells proliferated again and healed a wound. After 7 days of nutrient deprivation, monolayers were successfully passaged with trypsin and cells in L15/FBS grew to again form monolayers. Therefore, rainbow trout intestinal epithelial cells survived starvation, but barrier and wound healing functions were impaired.     

Composition of PCBs and PAHs in the Montreal Urban Community Wastewater and in the Surface Water of the St. Lawrence River (Canada)

Samples of treated wastewater drawn from the effluent of the Montreal Urban Community (MUC), Canada, and surface water samples from the St. Lawrence River were collected in 1993 and 1994 and analysed for PCBs and PAHs. The average concentrations of Σ13 PCBs and Σ14 PAHs in the effluent were 1.34 ± 0.71 ng L-1 and 326 ± 229 ng L-1, respectively. PCB concentrations in the effluent did not show any clear seasonal pattern in the effluent but PAH concentrations increased during the winter period. In the effluent plume, both PCB and PAH concentrations increased significantly between the upstream control site and the effluent outfall, and subsequently decreased. The profiles of PCB congeners were similar within the effluent plume and also among water masses of the St. Lawrence River. PAH profiles were also similar within the effluent plume, but were different across the two water masses of the St. Lawrence River. Based on the composition of PCB congeners, atmospheric inputs appear to represent the major source of PCBs in the St. Lawrence River. The sources of PAHs in the MUC effluent and in the St. Lawrence River water would appear to be, respectively, petroleum products and combustion-derived products.     

New bisbenzylisoquinoline alkaloid from Laureliopsis philippiana

Phytochemical investigation of Laureliopsis philippiana resulted in isolation of a new bisbenzylisoquinoline alkaloid (1) named laureliopsine A. The structure was established by spectroscopic methods, including 2D homo- and heteronuclear NMR experiments. This finding of a bisbenzylisoquinoline alkaloid in Laureliopsis supports its close relationship to Atherosperma and its taxonomic segregation from Laurelia.     

Effects of dopamine 2 receptor antagonist on sex steroid levels, oocyte maturation and spawning performances in Waigieu seaperch (Psammoperca waigiensis)

The present study has investigated the effects of domperidone (DOM), a dopamine 2 receptor antagonist, on plasma steroid hormone levels and reproductive performances of a female tropical marine finfish, Waigieu seaperch (Psammoperca waigiensis), with potential for cultivation in Vietnam. We showed that oral treatment of DOM during early stage of the reproductive cycle had no significant effects on the maturation and reproductive performances of the female fish, while plasma steroid hormone (testosterone (T), 11-ketotestosterone (11-KT), 17β-estradiol (E2) and progesterone (P)) levels were modulated based on month, DOM dose and the individual hormones measured. Overall, these findings suggest that DOM may not be needed for the induction of maturation and spawning of this species under aquaculture conditions. The data in the present study are significant in highlighting practical efforts for reducing drug use, production costs and for a sustainable aquaculture in a developing country such as Vietnam.     

Seasonal changes in hepatosomatic index,gonadosomatic index and plasma estradiol‐17β level in captively reared female rabbit fish (Siganus guttatus)

The seasonal changes in hepatosomatic index (HSI), gonadosomatic index (GSI) and plasma estradiol‐17β (E₂) level in female rabbit fish (Siganus guttatus) were investigated. The relationship between plasma E₂ levels with these indices and ovarian growth was also evaluated. Each month, at least 10 female broodfish were sacrificed to collect liver, ovary and blood for HSI, GSI and plasma E₂, respectively. GSI and HSI were calculated as percentage (%) of relative weight of gonad and liver to total body weight, respectively. Plasma E₂ level was measured using enzyme‐linked immunosorbent assay method (ELISA). Ovaries were cut and stained for histological observation. The results included seasonal changes in plasma E₂ levels, stages of ovarian development, GSI and HSI. The highest level of E₂ was observed in June (1,445.62 pg/ml) and during vitellogenesis (2,305 pg/ml). GSI and HSI values significant fluctuated monthly. The highest HSI and GSI were 1.72% in May and 3.58% in June, respectively. The pattern of plasma E₂ levels showed a relationship with GSI and different stages of ovarian development. HSI was associated with ovarian stages. During vitellogenesis, the highest value (1.9%) of HSI was observed. Histological sections showed that rabbit fish is a multiple spawner. These results contribute to further understanding of female rabbit fish reproductive biology in captivity. Important reproductive parameters such as HSI, GSI and E₂ can be used to indicate maturation status of this fish species.