亚太地区霉菌毒素:普遍性、负面影响、经济后果及其控制策略(下)

虽然矿物粘土类吸附剂价格上相对便宜．但某些原因使它们对被霉菌毒素污染的饲料及原料所起的保护作用非常有限(van Kessel和Hiang-Chek,200)。     

Geographical variation in rooting ability of stem cuttings of Azadirachta indica and Dalbergia sissoo

Geographical variations are among the least studied factors that control or modify rooting by cuttings. In the present study 1 year old branch cuttings of 12 provenances from Central India of Azadirachta indica and Dalbergia sissoo were examined for variation in rooting ability. Application of 500 mg/l-1 indole butyric acid (IBA) significantly increased (P < 0.05) root numbers, root length, root dry weight, rooting percentage, shoot number and shoot height. The auxin treatment amplified the provenance differences in rooting ability of cuttings. No significant variation in survival was evident with respect to provenance or auxin treatment. Correlation coefficients for root parameters were positive and significant (P < 0.01) and results of principal component analysis identified rooting factor having 52.3 and 46.7% of the total sub-plot mean variance among auxin treated cuttings for A. indica and D. sissoo, respectively. On the basis of overall performance of rooting in cuttings among provenances, the Raipur provenance was adjudged the best. Opportunities to develop genetically diverse clonal production stands are discussed.     

Unmethylated CpG oligodeoxynucleotides activate head kidney leukocytes of Atlantic cod, <Emphasis Type="Italic">Gadus morhua</Emphasis>

Bacterial DNA and synthetic oligodeoxynucleotides (ODNs) that contain unmethylated CpG motifs are strong inducers of immune response in most mammalian organisms. The use of these synthetic CpG motifs in fish, particularly in salmonids and carp, resulted in the modulation of their immune system. However, much less is known in other species of fish such as gadoids including Atlantic cod, Gadus morhua. Using head kidney (HK) leukocytes of cod in an in vitro study, we determined the effects of some established CpG-ODNs on the cellular responses of the fish immunocytes. Incubation of the HK leukocytes with 2 μM concentration of the CpG-ODNs resulted in enhanced respiratory burst. There were differential effects on the activities of acid phosphatase and cellular myeloperoxidase. Only CpG-ODN 1826 triggered a significant increase in the level of both enzymes. On the other hand, the supernatants derived from the HK leukocytes after incubation with different CpG-ODNs did not possess bactericidal activity against Vibrio anguillarum and Aeromonas salmonicida. This study has shown that CpG-ODNs at low concentrations are able to stimulate respiratory burst in cod but have minimal effects on cellular enzymatic activities and antibacterial action.     

Variation among New Zealand isolates of Sphaeropsis sapinea

Sphaeropsis sapinea is a pathogen of many coniferous species and causes significant losses to the plantation forestry industries of many countries. New Zealand isolates of S. sapinea were examined for colony and morphological characteristics, and pathogenicity to Pinus radiata seedlings. Considerable variation was observed in colony growth form and colour, and in the growth rates on four agar media. The conidial dimensions, carbon and nitrogen utilization, and pathogenicity also varied among the isolates. The variation observed was such that the isolates could not be placed within previously described distinct morphotypes and the present results concur with previous studies cautioning the use of morphological criteria alone to partition the species. These results contrast markedly with previous reports and seemingly indicate a change in the New Zealand S. sapinea population. This difference may reflect the re‐introduction or spread of additional isolates or a shift in the structure of the resident population.     

Further clarification of winter energy and protein requirements at the optimum feeding frequency for yellowtail

SUMMARY: This is another report from a series of studies aimed at determining the energy and protein requirements based on the optimum feeding frequency of yellowtail during the winter season. Experiments were conducted at Mie and Oita Prefectures, Japan, employing extruded pellets of known digestible energy (DE) and digestible protein (DP) values. Four groups of fish were fed at frequencies of five, three, two, and one time(s) per week. The most efficient feed performance was obtained for the feeding frequenecy of three times per week. The DE and DP requirements calculated based on the feeding rate at this frequency were 38.7 kcal and 2.8 g/kgBW per day (14.3–17.3°C) in Mie and 30.4 kcal and 2.2 g/kgBW per day (13.8–17.5°C) in Oita, respectively. The present results and the observations on the changes of the contents in digestive tracts tallied with our previous work, confirming that the optimum feeding frequency was three times per week.     

Delineation of chemically polluted groundwater regions in Visakhapatnam Basin,India

Water quality investigations were carried out in the Visakhapatnam basin to delineate groundwater pollution. It was observed that the groundwater in some localities of the basin is contaminated due to natural geological formation sources, industrial effluents, irrigation, and urbanization. The ring average method used in geophysical interpretation to separate regional and residual anomalies was modified and applied to the water quality data in the basin to locate chemically polluted groundwater regions. It is observed that the method can be applied successfully to delineate regions of groundwater pollution and it may also be helpful in identifying the sources.     

Embryo culture is an efficient way to conserve a medicinally important endangered forest tree species Strychnos potatorum

The present study reports a protocol for germination of Strychnos potatorum (ver. Tel. Chilla) using zygotic embryo culture as an embryo rescue method. A 100% germination rate was obtained by culturing the embryos on full-strength Murashige and Skoog’s medium (MS) containing 20 g/L sucrose in comparison to McCown and Lloyd’s Woody Plant Medium (WPM). Germination rates decreased when the sucrose concentration was lower or higher than 20 g·L-1 . WPM/MS medium containing glucose at levels 30, 20, 15 g·L-1 showed a smaller percentage of germination and at quarter strength, WPM/MS medium with glucose did not respond. Multiple shoot formation was found at 1.0 2.0 mg/L BAP; 3.0 mg/L Kn; 2.0 mg/L TDZ on MS medium with 20 g·L-1 sucrose. Germination rates improved when the embryos were placed upright (vertically) in the medium. The in vitro germinated seedlings were acclimatized in a walk-in-chamber and maintained in the green house with the survival rate of 65% 75%. These plants were transferred to the field and were found to be phenotypically normal, healthy and similar to donor plants. This protocol will be useful to overcome seed dormancy and for rapid multiplication and conservation of S. potatorum using zygotic embryo culture.     

Comparison of Diverse Differential Plating Methods to Enrich Bovine Spermatogonial Cells

Spermatogonial stem cells (SSC) have important applications in domestic animal reproduction and advanced biotechnologies. Because differential plating is one of the most common methods used for SSC enrichment, the goal of this study was to compare three differential plating methods for the enrichment of bovine SSC. To achieve this goal, testicular parenchyma from pre‐pubertal calves was minced and single cells were obtained after two enzymatic digestions. We compared three coating methods for differential plating: laminin (20 ng/ml), BSA (0.05 mg/ml) and PBS. Cells were incubated at 37°C, 5% CO₂ in air for 15 min onto laminin‐coated dishes or 2 h onto BSA‐ or PBS‐coated dishes. Cell viability was assessed by trypan blue exclusion method. Recovered cells were analysed for the expression of SSC molecular markers by quantitative RT‐PCR (GFRA1, CXCR4, ITGA6, THY1) and flow cytometry (GFRA1, CXCR4 and ITGA6). Cells at time 0, adherent cells on laminin and non‐adherent cells from BSA and PBS groups had the same cell viability (p = 0.0655). GFRA1, CXCR4 and THY1 relative gene expression was higher (p = 0.0402, p = 0.0007, p = 0.0117, respectively) for non‐adherent cells selected in PBS group. Flow cytometry analysis revealed that the presence of GFRA‐positive (GFRA+) cells was higher in non‐adherent cells from BSA and PBS groups (p < 0.001). However, laminin‐adherent cells had higher number of ITGA6+ cells (p < 0.001) and lower presence of CXCR4+ cells (p = 0.0012). In conclusion, differential plating is an effective method for the enrichment of bovine undifferentiated spermatogonia and higher expression of SSC markers is obtained without laminin or BSA coating.