Direct and indirect effects of resource quality on food web structure

The diversity and complexity of food webs (the networks of feeding relationships within an ecological community) are considered to be important factors determining ecosystem function and stability. However, the biological processes driving these factors are poorly understood. Resource quality affects species interactions by limiting energy transfer to consumers and their predators, affecting life history and morphological traits. We show that differences in plant traits affect the structure of an entire food web through a series of direct and indirect effects. Three trophic levels of consumers were influenced by plant quality, as shown by quantitative herbivore-parasitoid-secondary parasitoid food webs. We conclude, on the basis of our data, that changes in the food web are dependent on both trait- and density-mediated interactions among species.     

SOME PHYSIOLOGICAL CHARACTERISTICS AND THE AGRONOMIC IMPORTANCE OF DIPTERA DAMAGE TO GRASSES

Shoot-fly larvae cause considerable damage to cultivated grasses; it is greatest when overwintering tillers are lost, resulting in delayed emergence, decreased number of flowering heads and reduced yield of dry matter.
An increase in the number of tillers, which often follows the damage, cannot counter-balance the losses because the new tillers are smaller.
Different varieties within species, and different genotypes within varieties, show varying degrees of susceptibility to damage, and of capacity to recover from it. Favourable growing conditions promote recovery and reduce losses.
Non-cultivated grasses and unploughed leys are sources of infection, not only to cereals but also to cultivated grasses, and it is advisable not to put single plants or seed areas adjacent to old swards. The glasshouse is a special source of infection as it provides conditions favourable for the flies to produce extra generations at unusual times.
The importance of further investigations and the development of more economical protective techniques is stressed.     

Cardiorespiratory responses and plasma cortisol concentrations in dogs treated with medetomidine before undergoing ovariohysterectomy

OBJECTIVE: To evaluate effects of medetomidine on anesthetic dose requirements, cardiorespiratory variables, plasma cortisol concentrations, and behavioral pain scores in dogs undergoing ovariohysterectomy. DESIGN: Randomized, prospective study. ANIMALS: 12 healthy Walker-type hound dogs. PROCEDURE: Dogs received medetomidine (40 micrograms/kg [18.2 micrograms/lb] of body weight, i.m.; n = 6) or saline (0.9% NaCl) solution (1 ml, i.m.; 6) prior to anesthesia induction with thiopental; thiopental dose needed for endotracheal intubation was compared between groups. Ovariohysterectomy was performed during halothane anesthesia. Blood samples were obtained at various times before drug administration until 300 minutes after extubation. Various physiologic measurements and end-tidal halothane concentrations were recorded. RESULTS: In medetomidine-treated dogs, heart rate was significantly lower than in controls, and blood pressure did not change significantly from baseline. Plasma cortisol concentrations did not increase significantly until 60 minutes after extubation in medetomidine-treated dogs, whereas values in control dogs were increased from time of surgery until the end of the recording period. Control dogs had higher pain scores than treated dogs from extubation until the end of the recording period. CONCLUSION AND CLINICAL RELEVANCE: Administration of medetomidine reduced dose requirements for thiopental and halothane and provided postoperative analgesia up to 90 minutes after extubation. Dogs undergoing ovariohysterectomy by use of thiopental induction and halothane anesthesia benefit from analgesia induced by medetomidine administered prior to anesthesia induction. Additional analgesia is appropriate 60 minutes after extubation.     

Activin stimulates goldfish FSH biosynthesis by enhancing FSHβ promoter activity

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play critical roles in controlling vertebrate gonadal development and function. Activin, a dimeric growth factor initially identified in the gonads, is important in the differential regulation of the two gonadotropins in mammals. Using goldfish as a model, we have demonstrated that activin stimulates FSHβ but suppresses LHβ expression. The present study demonstrated that the 5′-flanking region of goldfish FSHβ gene is functional in the mouse gonadotrope cell line, LβT2 cells. Similar to its effect on the cultured pituitary cells, activin stimulated FSHβ promoter activity in the LβT2 cells and the effect could be blocked by its binding protein follistatin. Follistatin also significantly suppressed the basal FSHβ promoter activity, suggesting secretion of endogenous activin by the LβT2 cells. Further characterization of the cis-regulatory elements responsible for activin stimulation is now under way in our laboratory.     

Novel 1,3,5-triazine derivatives with herbicidal activity

New fluoroalkyl-substituted 1,3,5-triazine derivatives were synthesized and screened for herbicidal activity using a greenhouse pot test. Surprisingly, a series of 2-alkyl-4-fluoroalkyl-6-aralkylamino-1,3,5-triazines e.g. 6-(4-bromobenzylamino)-2-methyl-4-trifluoromethyl-1,3,5-triazine was found to possess strong pre- and post-emergence herbicidal activities, although the conventional herbicidal 1,3,5-triazines generally should have a 2-substituted-4,6-diamino-1,3,5-triazine structure for herbicidal activity. Our compounds show strong Photosynthetic Electron Transport inhibitory activity (PI₅₀ c 7). Although their herbicidal effect is considered to be caused by a process similar to that for the conventional 1,3,5-triazine herbicide atrazine, they can control atrazine-resistant Chenopodium album effectively, and will thus form promising trial compounds for new triazine herbicide design.     

Efficacy of leflunomide for treatment of refractory inflammatory colorectal polyps in 15 Miniature Dachshunds

Inflammatory colorectal polyp (ICRP), common in miniature dachshunds, presents with hematochezia, tenesmusand mucoid feces. Although an 80% response rate has been reported when treated with prednisolone andcyclosporine, effective treatment is needed for the remaining 20% of ICRP dogs. Leflunomide is animmunosuppressive drug reported as effective in several immune-mediated diseases. In the present study, weretrospectively evaluated the efficacy and adverse effects of leflunomide in 15 ICRP dogs that were refractoryto treatment with prednisolone and cyclosporine. Treatment efficacy was assessed by endoscopy, clinicalsymptoms and rectal palpation. Adverse effects were determined by clinical symptoms and blood testing duringfollow-up. The leflunomide treatment response rate was 93.3%. The median dosage of leflunomide and the medianresponse time were 3 mg/kg (range: 1.7–4.0 mg/kg) and 35 days (range: 20–119 days), respectively. Adverseeffects observed included lethargy (3 dogs), anorexia (1 dog), respiratory symptoms (1 dog), leukocytopenia (2dogs), thrombocytopenia (1 dog), anemia (1 dog) and liver enzyme elevation (8 dogs). Most of the adverseeffects improved with symptomatic treatment and leflunomide discontinuation or dosage reduction. Inconclusion, leflunomide treatment is effective in ICRP dogs refractory to treatment with prednisolone andcyclosporine. Because several adverse effects were observed, close monitoring is needed during leflunomidetreatment follow-up.     

Paeoniflorin: an antihyperlipidemic agent from Paeonia lactiflora

Paeoniflorin (1), isolated from the methanol extract of Paeonia lactiflora, showed a lowering effect on cholesterol level in the experimentally-induced hyperlipidemic rats. Paeoniflorin showed a significantly lowering effect of total cholesterol, LDL and triglyceride levels compared with the control group at the dose of 200 and 400 mg/kg, p.o. once a day for 4 weeks.     

Acute haemolysis associated with etomidate-propylene glycol infusion in dogs

Acute haemolysis occurred in medetomidine-atropine premedicated dogs (n=6) after infusion of etomidate in 35% propylene glycol (etomidate-PG). Free plasma haemoglobin concentration was 12.0 +3.5 μg/dl at baseline. After premedication (medetomidine 15 μg/kg, IM; atropine 0.044 mg/kg, IM) values were 14 ± 5.2 and 20 ± 4.8 mg/dl, at 5 and 10 minutes, respectively. Plasma haemoglobin values increased significantly (p±0.05; 121 +24.2 mg/dl) 5 minutes after etomidate-PG loading dose (0.5 mg/kg) and infusion (50μg/kg/min) and remained significantly elevated (127 ± 12.7 to 310.6 ± 69.3 mg/dl) throughout the 60-minute infusion period. Acute haemolysis was also observed in dogs (n=3) that received etomidate-PG infusion alone (2 mg/kg loading dose followed by 110 μg/ kg/ min constant infusion). In addition, fresh dog blood (n=3) was incubated alone or with either 0.9% saline or etomidate-PG in test tubes for 5 minutes and free plasma haemoglobin concentration measured. Free plasma haemoglobin concentrations were 18.3 ± 6.8, 11.7 +4.5 and 1712.0 ± 309.6 mg/dl for blood alone, saline-blood and etomidate-PG-blood, respectively. It was concluded that etomidate-PG caused acute haemolysis in dogs both in vivo and in vitro. The clinical significance of this amount of haemolysis is not clear at this time and thus, requires further study.     

PTP1B Inhibitory and Anti-Inflammatory Effects of Secondary Metabolites Isolated from the Marine-Derived Fungus Penicillium sp. JF-55

Protein tyrosine phosphatase 1B (PTP1B) plays a major role in the negative regulation of insulin signaling, and is thus considered as an attractive therapeutic target for the treatment of diabetes. Bioassay-guided investigation of the methylethylketone extract of marine-derived fungus Penicillium sp. JF-55 cultures afforded a new PTP1B inhibitory styrylpyrone-type metabolite named penstyrylpyrone (1), and two known metabolites, anhydrofulvic acid (2) and citromycetin (3). Compounds 1 and 2 inhibited PTP1B activity in a dose-dependent manner, and kinetic analyses of PTP1B inhibition suggested that these compounds inhibited PTP1B activity in a competitive manner. In an effort to gain more biological potential of the isolated compounds, the anti-inflammatory effects of compounds 1–3 were also evaluated. Among the tested compounds, only compound 1 inhibited the production of NO and PGE₂, due to the inhibition of the expression of iNOS and COX-2. Penstyrylpyrone (1) also reduced TNF-α and IL-1β production, and these anti-inflammatory effects were shown to be correlated with the suppression of the phosphorylation and degradation of IκB-α, NF-κB nuclear translocation, and NF-κB DNA binding activity. In addition, using inhibitor tin protoporphyrin (SnPP), an inhibitor of HO-1, it was verified that the inhibitory effects of penstyrylpyrone (1) on the pro-inflammatory mediators and NF-κB DNA binding activity were associated with the HO-1 expression. Therefore, these results suggest that penstyrylpyrone (1) suppresses PTP1B activity, as well as the production of pro-inflammatory mediators via NF-κB pathway, through expression of anti-inflammatory HO-1.     

Cryopreservation of Sperm of Farmed European Eel Anguilla anguilla

Sexual maturation and sperm release were induced in farmed European eels Anguilla anguilla kept exclusively in fresh water by using two dosages of human chorion gonadotropin (100 International Unit (IU)-Group one and 250 IU/individual per week-Group two). Sperm release took over 13 wk in both groups. The quality of sperm was investigated on the eighth, ninth, and tenth wk. The average cell densities were 0.94 ± 0.4 × 1010 (Group one) and 0.93 to. ± 0.6 × 10¹⁰ (Group two) spermatozoa/mL. The estimated motility of eel sperm was 33, 55, and 49% on the eighth, ninth, and tenth wk of treatment, respectively. The estimated average motility of samples selected for cryopreservation was 73 ± 10%, while the post-thaw motility of cryopreserved samples was 36 ± 11%. The extender originally developed for common carp sperm crypreservation together with methanol as cryoprotectant was found suitable for the cryopreservation of European eel sperm.