Identification of pinnatoxins and discovery of their fatty acid ester metabolites in mussels ( Mytilus edulis ) from eastern Canada

Pinnatoxins are a group of fast-acting cyclic imine toxins previously identified in shellfish from Asia, the southern Pacific, and northern Europe. In this work pinnatoxins were detected in mussels from locations across the eastern coast of Canada. Pinnatoxin G (6) was the major structural variant present, sometimes at levels >80 μg/kg, whereas much lower levels of pinnatoxin A (1) were detected in some samples. Increased concentrations were observed following base hydrolysis of extracts, leading to the discovery by LC-MS of a range of fatty acid esters of 6. Information on the structures of these acylated derivatives was provided through a series of mass spectrometric experiments, supported by partial synthesis, and it is proposed that the compounds are 28-O-acyl esters of 6. Although acyl esters of a range of other phycotoxins are known to form as metabolites in shellfish, this is the first report of their existence for this particular toxin class. The occurrence of pinnatoxins in North American shellfish further highlights the international distribution of these toxins.     

高寒草甸草地水、土、草中氮硫含量冷暖季节的变化

根据青海高原特殊的气候分布特征，把高寒草甸草地绵羊放牧地划分为冷季和暖季。通过测定冷暖绵羊放牧地水、土壤、牧草中氮和硫含量的结果表明：水、土壤、牧草中氮和硫的含量暖季＞冷季（P＜0．05），其中地表水冷季含硫量分别为3．7mg/kg、5.1mg/kg，水中没有检测到氮；牧草中硫含量冷暖季分别为2952mg/kg,3262mg/kg，差异显著（P＜0．05）；牧草中氮含量冷暖季分别为0．62％、1．36％，差异显著（P＜0．05）；土壤氮含量冷暖季分别为0．22％、0．285％，差异显著（P＜0．05）；硫含量冷暖季分别为0．24％、0．37％。     

Maturation Status, Protein Synthesis and Developmental Competence of Oocytes Derived from Lambs and Ewes

The efficacy of oocyte selection for in vitro embryo production depends on the abundance and diameter of follicles, cumulus layers around the oocytes and subsequent fertilization. Application of `ovum pick-up' technique allows us to utilize partially matured oocytes for embryo production even from juvenile subjects. To compare their developmental competence, oocytes derived from lambs and ewes and cultured in maturation medium for up to 26 h were assessed at 2 h intervals by confocal microscopy after chromatin and microtubulin-specific fluorochrome labelling. Lamb oocytes reached second meiotic metaphase (MII) at lower numbers at 24 h (60.0%) and 26 h (28.6%) whereas 85.7% of adult-derived oocytes attained MII status by 24 h of maturation. Radiolabelling of oocyte proteins revealed higher incorporation of [³⁵S-]-methionine and [³⁵S]-cysteine in adult-derived oocytes compared to lamb oocytes. Although the cleavage rate of lamb oocytes was similar to that of ewe oocytes, the proportion reaching blastocyst stage was significantly lower (p < 0.05) in the lamb-derived oocytes. However, blastocysts from both types of oocytes displayed similar cell lineage allocations to inner cell mass and trophectoderm.     

Effects of drug residues in the faeces of cattle treated with injectable formulations of ivermectin and moxidectin on larvae of the bush fly, Musca vetustissima and the house fly, Musca domestica

Objective: To assess the toxicity of residues of ivermectin and moxidectin in cattle faeces collected at intervals after treatment.
Design: Replicated bioassays of faeces using larvae of the bush fly, Musca vetustissima and the house fly, Musca domestica .
Animals: Two groups of five Murray Grey x Aberdeen Angus steers were treated with injectable formulations of ivermectin and moxidectin respectively. A third group was used as an untreated control.
Procedure: Newly emerged fly larvae were reared in the dung of treated animals.
Results: Drug residues in faeces collected 3 to 35 days after treatment with an injectable formulation of moxidectin had no significant effect on the survival of larvae of M vetustissima . Similarly, faeces dropped up to seven days after treatment caused no significant reduction in larval survival in M domestica . In day 2 dung, residues of moxidectin delayed development of M vetustissima larvae, but had no effect on their survival. In contrast, ivermectin-treated steers, produced dung that inhibited larval development of both M vetustissima and M domestica for 7 to 14 days after treatment. Significant reductions in survival of M vetustissima larvae occurred in dung collected on days 21 and 28 after treatment, but by day 35 survival did not differ from that in control dung.
Conclusion: Excreted faecal residues of moxidectin are relatively innocuous to larvae of both M vetustissima and M domestica . Those of ivermectin inhibit survival for 7 to 14 days after treatment and are likely to have adverse effects on non-target organisms.     

Ovarian Responses, Hormonal Profiles and Embryo Yields in Anoestrous Ewes Superovulated with Folltropin®-V after Pretreatment with Medroxyprogesterone Acetate-releasing Vaginal Sponges and a Single Dose of Oestradiol-17β

In ruminants, superovulatory treatments started at the time of follicular wave emergence result in greater and less variable ovulatory responses and embryo yields compared with the treatments begun in the presence of a large growing antral follicle(s) from the previous waves. The progesterone–oestradiol treatment is routinely used for follicular wave synchronization in cattle. The main objective of this study was to characterize the ovarian responses, hormonal profiles and in vivo embryo production in anoestrous Rideau Arcott ewes (May‐June), which were superovulated after pretreatment with medroxyprogesterone acetate (MAP)‐releasing intravaginal sponges and a single dose of oestradiol‐17β (E₂‐17β). Six days after insertion of MAP sponges, eight ewes were given an i.m. injection of 350 μg of E₂‐17β (E₂‐17β‐treated ewes); 10 ewes were given an i.m. injection of vehicle (control ewes). Multiple‐dose Folltropin®‐V treatment, followed by the bolus injection of GnRH (50 μg i.m.), began 6 days after E₂‐17β/vehicle injection. Transrectal ovarian ultrasonography revealed that: (i) the interval between E₂‐17β/vehicle injection and regression of all follicles ≥5 to 3 mm in diameter was shorter (p < 0.01; 2.6 ± 0.4 vs 4.8 ± 0.6 days respectively); and (ii) the interval between injection and emergence of the next follicular wave was longer (p < 0.05; 5.4 ± 0.3 vs 1.2 ± 0.4 days, respectively) in E₂‐17β‐treated than in control ewes. During the 6 days after injection, the mean FSH peak concentration and basal FSH concentration were lower (p < 0.01) in E₂‐17β‐treated ewes. The mean ovulation rate and the number of recovered embryos did not differ (p > 0.05) between the two groups of ewes. However, the number of luteinized unovulated follicles per ewe, and the variability in the number of luteal structures and overall embryo yield were less (p < 0.05) in E₂‐17β‐treated compared with control ewes. In conclusion, the MAP–E₂‐17β pretreatment significantly reduced the variability in ovarian responses and embryo yields, without affecting the embryo production in superovulated anoestrous ewes.     

Optical sensing and chemometric analysis of soil organic carbon – a cost effective alternative to conventional laboratory methods?

Soil organic carbon (SOC) is frequently determined by the Walkley‐Black (WB) method. A limitation of the test is incomplete oxidation of the carbon fraction and underestimation of SOC. Automated dry combustion methods are expensive and slow. Optical sensing and chemometric analysis offer the potential of an economical method capable of quantifying SOC fractions. The aim of this study was to identify the best SOC analysis method to facilitate maximum sampling resolution based on the cost per sample, analytical accuracy and time. A comparative evaluation was made of five techniques; (1) the WB method, (2) total combustion by total organic C analyser, (3) infrared (IR) diffuse reflectance spectroscopy, (4) a portable spectroradiometer and (5) laboratory hyperspectral imaging. This involved assessing equipment costs, consumables and time to derive total analytical cost. The benefits were sample throughput and analytical accuracy. Instrumentation represented the largest input to analytical cost and for optical methods was governed by the spectral range. In contrast to dry combustion, this cost is offset by high sample throughput and minimal consumable requirements for IR spectroscopy and hyperspectral imaging. Hyperspectral imaging is identified as the most rapid technique with potential to scan about 720 samples per day at 90% less cost than the WB method. The opportunity cost of hyperspectral imaging is to forfeit some analytical accuracy associated with the dry combustion method. Dry combustion, despite its high cost per sample, incurs no further costs associated with updating prediction models or developing site or soil specific correction factors.     

Rapid calcitonin response to experimental hypercalcemia in healthy horses

Calcium has important physiological functions, and disorders of calcium homeostasis are frequent in horses. We have made important progress understanding equine calcium homeostasis; however, limited information on equine calcitonin (CT) is available, in part because of the lack of validated CT assays. To determine the CT response to high ionized calcium (Ca²⁺) concentrations in healthy horses, we induced hypercalcemia in 10 healthy horses using a calcium gluconate 23% solution (5 mg/kg; 120 mL/500 kg horse) infused over 4 min. Four horses were infused with 120 mL of 0.9% NaCl and used as controls. We validated a human-specific CT radioimmunoassay for use in horses. Serum Ca²⁺ concentrations increased from 6.2 ± 0.3 mg/dL to 9.9 ± 0.5 mg/dL (4 min; P < 0.01). Serum CT increased from 16.7 ± 8.0 pg/mL to 87.1 ± 55.8 pg/mL at 2 min, and 102.5 ± 51.1 pg/mL at 4 min (P < 0.01). Serum CT returned to baseline by 20 min, whereas serum Ca²⁺ returned to baseline by 40 min. Of interest, CT concentrations returned to baseline despite hypercalcemia, suggesting thyroid gland C-cell CT depletion. Resting CT values higher than 40 pg/mL were considered abnormally elevated. No significant changes in serum Ca²⁺ or CT concentrations were found in control horses. The coefficients of variation for the CT radioimmunoassay were lower than 11.9%. We conclude that the equine thyroid gland C-cell responds quickly to changes in extracellular Ca²⁺ concentrations by secreting large quantities of CT into the systemic circulation, indicating that CT is important in equine calcium homeostasis. The human CT radioimmunoassay can be used to measure changes in equine CT.     

Effect of increasing the time between slurry application and first rainfall event on phosphorus concentrations in runoff

Minimizing slurry phosphorus (P) losses in runoff requires careful management in the context of both soil P surpluses and changing patterns in rainfall. Increasing the time interval between slurry application and the first rainstorm event is known to reduce P loss in runoff although the risk period for elevated P concentrations in runoff can extend for weeks. This study investigated the impact of increasing the time interval between slurry application and first rainstorm event on P concentrations in runoff. Simulated rainfall (40 mm h⁻¹) was applied at 2, 4, 10, 18, 30 and 49 days after dairy slurry was surface-applied to a grassland sward in Ireland. Increasing time to runoff resulted in a decrease in dissolved reactive P concentrations from 5.0 to 1.0 mg P L⁻¹ and a P signal in runoff for 18 days. Beyond 18 days, elevated P concentrations were observed in runoff collected from natural rainfall that preceded the day 49 rainstorm event. A published surface phosphorus and runoff model (SurPhos) was used to understand the slurry P dynamics controlling P interactions with runoff. Dissolved reactive P in runoff was predicted with accuracy by SurPhos, R² = .89. The SurPhos model implied that slurry P mineralization occurred during the experimental period that resulted in a small spike in P concentrations beyond the defined risk period. This study shows that the experimental data have the potential to be extrapolated to different weather scenarios using SurPhos and could test when and where slurry P could be most safely spread.     

日粮核苷酸对早期断奶小鼠肝脏基因表达的影响

研究了日粮核苷酸对早期断奶小鼠肝脏基因表达的影响:选取16～17日龄健康BALB/C雄性小鼠60只,分成对照组和实验组,分别饲喂添加0、0.25%核苷酸的无核苷酸基础日粮,在实验的第2、4、10天采用差异显示技术分离小鼠肝脏中差异表达的基因。结果表明:采用6对引物分离到4条差异表达的基因片断。采用差异显示技术初步分离到4个受核苷酸影响差异表达的基因,这些片段需要做进一步的验证。